Random Polarity Suppression (RPS)

• Random Polarity Suppression (RPS) is an interpretive term describing methods that lessen polarity reversal effects in astrophysical systems and semiconductor epitaxy.
• In celestial mechanics, RPS involves modulating stochastic stellar-jet forcing to suppress resonance excitation and reduce orbital inclination growth.
• In III-nitride epitaxy, controlling supersaturation and substrate orientation effectively suppresses inversion domain defects for improved material interfaces.

Random Polarity Suppression (RPS) is not a standardized term in the cited arXiv literature. In the available corpus, it is best treated as an interpretive label for mechanisms that suppress, prevent, or comparatively weaken polarity reversal or polarity inversion phenomena. Two technically substantive contexts support such an interpretation. In celestial mechanics, stochastic stellar-jet forcing can produce a relative suppression of resonant orbital excitation when random polarity reversals destroy the temporal coherence needed for resonance crossing (Namouni, 2012). In III-nitride epitaxy, unintentional opposite-polarity inversion domains in nominally N-polar films can be totally suppressed by combining low Al supersaturation with step-flow growth on $4^\circ$ off-axis C-face $4H$-SiC $(000\bar{1})$ (Zhang et al., 2022). The same acronym, however, also denotes “restricted phase space” thermodynamics, “Reactor Protection System,” and Rock-Paper-Scissors-type games in unrelated arXiv papers, so terminological disambiguation is indispensable (Sadeghi et al., 2023, Liu et al., 2015, Maimon, 1 Nov 2025).

1. Terminological status

The phrase “Random Polarity Suppression” does not appear as an explicit formalism in the stellar-jet paper (Namouni, 2012), and the III-nitride paper does not use the acronym RPS either (Zhang et al., 2022). The first paper is fundamentally about stochastic stellar-jet momentum loss with periodic polarity reversal and random polarity reversal; the second is about polarity control by inversion domain suppression in N-polar III-nitride heterostructures. In both cases, any connection to “Random Polarity Suppression” is interpretive rather than author-defined.

An Editor’s term, “interpretive RPS,” is useful for separating this umbrella usage from the acronym’s unrelated meanings in other fields. Under that interpretive usage, RPS does not denote a single equation set or universally accepted framework. Instead, it denotes a family of situations in which polarity fluctuations, polarity inversion events, or polarity-related disorder are weakened, eliminated, or rendered dynamically ineffective. The key distinction is that the stellar-jet work treats suppression as conditional and relative, whereas the epitaxy work treats suppression as process-level elimination of unintended inversion domains.

This distinction is conceptually important. In the orbital-dynamics case, random polarity does not generically suppress excitation; for constant variability timescales it can enhance excitation. In the epitaxial case, by contrast, suppression means preventing the appearance of opposite-polarity regions at the nucleation stage. The same phrase therefore spans two different technical meanings: comparative weakening of a response and direct suppression of defect formation.

2. Stochastic polarity reversal in stellar-jet forcing

In the dynamical model of planetary excitation by asymmetric stellar jets, a planet orbits a gravitating central mass subject to an additional acceleration ${\bm A}$ generated by stochastic momentum loss from the star+inner-disk system (Namouni, 2012). The governing equation of motion is

$$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$

where ${\bm x}$ and ${\bm v}$ are the planet’s position and velocity relative to the star, and $M$ is the stellar mass plus any inner-disk mass inside the jet-launching region. The characteristic acceleration scale is estimated by

$A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$

The stochastic forcing is implemented as piecewise constant acceleration over intervals of length $\tau$, the variability time scale. The acceleration is “drawn from a normal distribution with zero mean and finite standard deviation $4H$0 after a time $4H$1. Acceleration remains constant for the duration $4H$2.” Two reversal rules are then defined. In periodic polarity reversal, acceleration profiles are “constructed from a normal distribution that is forced to reverse with the period $4H$3.” In random polarity reversal, “the latter forcing is turned off.” This asymmetry is central: in the periodic case, $4H$4 is the sign-reversal timescale; in the random case, $4H$5 is only a minimum reversal timescale because the sign can persist across several adjacent intervals by chance.

The forcing strength is parameterized by the keplerian boundary semimajor axis

$4H$6

Smaller $4H$7 corresponds to stronger stochastic forcing. Because the jet axis is chosen orthogonal to the initial orbital plane, ordinary secular forcing with $4H$8 is deliberately removed, and excitation arises only from stochastic temporal variability. For one constant-acceleration interval, under $4H$9,

$(000\bar{1})$0

and the random-walk scaling becomes

$(000\bar{1})$1

The paper further states that $(000\bar{1})$2 and $(000\bar{1})$3 scale as $(000\bar{1})$4, which is why inclination dominates the response.

A major result is the planet–jet variability resonance near

$(000\bar{1})$5

described verbally as a “novel excitation resonance between a planet’s orbital period and the jet’s variability timescale where the former equals twice the latter.” For Jupiter at $(000\bar{1})$6 AU, with $(000\bar{1})$7 years, resonance is near $(000\bar{1})$8 years, while $(000\bar{1})$9 years corresponds to a minimum of excitation. This is the first suppression-like feature: the paper presents minima in the resonance curve produced by phase cancellation, not a named suppression principle.

The second and more important suppression-like feature appears during resonance crossing when the variability time scale evolves from ${\bm A}$0 yr to ${\bm A}$1 yr. The paper considers a square-root law,

${\bm A}$2

and an exponential law,

${\bm A}$3

For constant ${\bm A}$4, “Random polarity reversal appears to cause greater excitation for constant variability timescales,” because one-signed forcing can persist across multiple intervals. During resonance crossing, however, “Unlike the case of constant variability time scales, it is periodic and not random polarity reversal that achieves the strongest excitation amplitudes.” The maximum inclination in periodic-crossing cases can reach about ${\bm A}$5, whereas for random reversals the maximum inclination is even smaller than those with constant variability timescales. In the same regime, “substantial outward migration is absent” for random reversals. This supports an interpretive notion of relative suppression: random reversals aid stochastic diffusion at fixed ${\bm A}$6, but they reduce coherent resonant pumping when ${\bm A}$7 sweeps through ${\bm A}$8.

The paper also identifies suppression by crossing too fast. With ${\bm A}$9 AU and the square-root law, strong periodic excitation begins after $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$0 years; for $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$1 AU it is delayed to $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$2 years. With the faster exponential crossing, strong excitation for $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$3 AU is delayed to $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$4 years, and the triggering crossing velocity is quoted as $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$5. In this dynamical setting, then, “suppression” is best understood as reduced excitation produced by phase minima, excessively rapid resonance passage, or phase disorder introduced by random reversals.

3. Inversion-domain suppression in N-polar III-nitride epitaxy

The most direct materials-science realization of polarity suppression in the supplied corpus concerns nitrogen-polar III-nitride heterostructures grown on C-face $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$6-SiC $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$7 (Zhang et al., 2022). The central problem is the unintentional formation of metal-polar inversion domains (IDs) inside nominally N-polar AlN nucleation layers. These opposite-polarity inclusions are bounded by inversion domain boundaries, can have inclined or horizontal geometry, and may evolve into pyramidal features extending toward the film surface. The paper states that such polarity disorder compromises the sharpness and polarity integrity of interfaces that are crucial for N-polar HEMT operation.

The suppression strategy is process-driven. The study compares low-temperature (LT) AlN nucleation layers grown at $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$8 with high-temperature (HT) AlN nucleation layers grown at $$\frac{\rm d} {\bm v}{{\rm d} t}=-\frac{GM}{|{\bm x}|^3}\,{\bm x} +{\bm A},$$9 on on-axis SiC and ${\bm x}$0 on ${\bm x}$1 off-axis SiC. All AlN nucleation layers were grown for ${\bm x}$2 min at ${\bm x}$3 mbar, with mixed ${\bm x}$4 carrier gas and V/III ratio of ${\bm x}$5, after hydrogen etch at ${\bm x}$6 and NH${\bm x}$7 preflow. The governing idea is that high supersaturation favors ${\bm x}$8D island nucleation, while lower supersaturation favors ordered lateral growth; the substrate miscut then determines whether that lower-supersaturation regime develops into ${\bm x}$9D layer-by-layer growth or step-flow growth.

The decisive result is that IDs are totally suppressed only for HT AlN nucleation on the ${\bm v}$0 off-axis substrate, where growth proceeds in step-flow mode. On-axis HT AlN improves polarity but does not fully eliminate inversion domains: AFM gives RMS roughness ${\bm v}$1 nm, yet STEM still reveals a low density of large inverted pyramidal Al-polar domains extending toward the surface. By contrast, HT off-axis AlN at ${\bm v}$2 shows step-flow morphology with RMS roughness ${\bm v}$3 nm, pyramid-free growth, an atomically sharp AlN/SiC interface, and pure N-polar stacking. This is the paper’s strongest suppression claim.

The low-temperature contrast is equally important. At ${\bm v}$4, both on-axis and ${\bm v}$5 off-axis samples grow in ${\bm v}$6D island mode and show mixed polarity. AFM reports RMS roughness ${\bm v}$7 nm for LT on-axis and ${\bm v}$8 nm for LT off-axis. Atomically resolved ADF-STEM shows that initial layers at the SiC interface are dominantly N-polar, but after only a few layers irregular and lateral inversion domain boundaries form and Al-polar regions become dominant. In off-axis LT AlN, steep pyramidal structures with inclined IDBs are seen; in on-axis LT AlN, both inclined and horizontal IDBs appear, and the upper part becomes Al-polar-dominated.

The thermodynamic control variable is Al supersaturation, qualitatively defined by the relative difference between the input Al partial pressure and the equilibrium Al vapor pressure,

${\bm v}$9

with hydrogen fraction

$M$0

The paper calculates $M$1 using Al partial pressure $M$2 mbar, total pressure $M$3 mbar, and N-rich chemistry, and reports three critical trends: increasing V/III ratio up to $M$4 increases Al supersaturation by about one order of magnitude; increasing temperature from $M$5 to $M$6 decreases Al supersaturation by about five orders of magnitude; and small additions of H$M$7 can significantly reduce supersaturation, especially at low V/III ratio or in lower-temperature regimes. The transition to step-flow on the off-axis substrate occurs once supersaturation falls below $M$8. Transition to $M$9D growth on the on-axis substrate requires still lower supersaturation, below $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$0, with the experimentally cited value $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$1.

The physical interpretation combines thermodynamics, kinetics, and local polarity selection. Lower supersaturation suppresses the driving force for $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$2D island nucleation. The $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$3 off-axis substrate increases step density and kink density, so adatoms are captured at steps more effectively and step-flow can occur at $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$4, whereas on-axis growth needed $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$5 merely to transition away from $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$6D islanding. The paper relates this to the Burton-Cabrera-Frank framework. It also states explicitly that $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$7D island formation provides multi-planar orientations exposed during growth, which likely increase the probability of oxygen incorporation, leading to polarity inversion. In this setting, polarity suppression is achieved indirectly by suppressing the island morphology that seeds inversion.

4. Diagnostics, evidence, and operational meaning of suppression

The evidentiary structure differs sharply between the orbital and epitaxial contexts. In the stellar-jet paper, suppression is inferred from comparative orbital outcomes such as reduced inclination growth, reduced migration, or resonance minima (Namouni, 2012). Diagnostics include the final or mean values of orbital eccentricity $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$8, inclination $A \sim 10^{-13}\, \left(\frac{\dot M}{10^{-8} M_\odot\, \mbox{\rm yr}^{-1}}\right)\, \left(\frac{v_e}{300 \,\mbox{\rm km\,s}^{-1}}\right)\, \left(\frac{M_\odot}{M}\right) \mbox{\rm km\,s}^{-2}.$9, semimajor-axis migration $\tau$0, and the star’s residual velocity $\tau$1. The residual velocity is mainly a numerical or physical consistency check, and enough realizations are used so that its mean and dispersion stay below a few km/s. Here “suppression” means a smaller dynamical response under a specific stochastic protocol.

In the III-nitride paper, suppression is structural and local rather than purely macroscopic (Zhang et al., 2022). AFM classifies growth mode and roughness; SEM supports morphology assessment; KOH etching and HR-XRD provide conventional polarity probes; and atomically resolved ADF-STEM is the decisive method because it directly tracks the Al/N stacking sequence along the $\tau$2-axis and reveals the presence, geometry, and density of inversion domains and boundaries. The paper explicitly warns that KOH can be misleading in mixed-polar AlN because adjacent N-polar pyramids can under-etch or over-etch neighboring Al-polar domains, causing those domains to escape detection. In that sense, suppression must be demonstrated atomically rather than inferred from bulk polarity tests alone.

The distinction matters for how the term should be used. In the orbital problem, a suppression claim is meaningful only relative to a baseline: periodic versus random reversals, slow versus fast resonance crossing, or resonance maximum versus resonance minimum. In the epitaxial problem, the phrase denotes the disappearance of a defect class in the examined STEM sections under a specific growth mode. This suggests that any generalized RPS vocabulary should distinguish between comparative suppression of a response and elimination of a nucleation pathway.

The same distinction extends to multi-body effects. In the two-planet stellar-jet calculations, mutual perturbations erase some excitation minima seen for a single planet, and under resonance crossing random reversals again produce smaller amplitudes than periodic ones. In the epitaxial case, once the nucleation layer is controlled, polarity continuity is retained across the overgrown heterostructure: cross-sectional ADF-STEM shows N-polar AlN/SiC, N-polar GaN/AlN, and N-polar AlGaN/GaN interfaces, all atomically sharp.

5. Acronym collisions and disciplinary disambiguation

The acronym RPS is heavily overloaded in the supplied literature. This is not a minor editorial issue, because the technical content associated with the acronym changes completely from one field to another.

arXiv id	Meaning of “RPS”	Domain
(Sadeghi et al., 2023)	restricted phase space	AdS black-hole thermodynamics
(Liu et al., 2015)	Reactor Protection System	nuclear reactor instrumentation and control
(Maimon, 1 Nov 2025)	Rock-Paper-Scissors	discrete game theory
(Namouni, 2012)	not used as “RPS”	stochastic stellar-jet polarity reversal
(Zhang et al., 2022)	not used as “RPS”	inversion domain suppression in III-nitrides

In “Bulk-boundary and RPS Thermodynamics from Topology perspective,” RPS explicitly means restricted phase space thermodynamics, with fixed AdS radius $\tau$3, no pressure-volume term, and a first law

$\tau$4

leading to a single critical point with topological charge $\tau$5 for the black holes studied (Sadeghi et al., 2023). This has no polarity content.

In “Test study on the RPS of TMSR-SF1 reactor,” RPS means Reactor Protection System, described as a 1E-level safety system with triple-modular redundancy and 2-out-of-3 voting logic (Liu et al., 2015). Again, the acronym overlap is accidental.

In “Different Forms of Imbalance in Strongly Playable Discrete Games I: Two-Player RPS Games,” RPS denotes Rock-Paper-Scissors-type tournament games with antisymmetric payoff matrices and totally mixed equilibrium as the operational criterion for playability (Maimon, 1 Nov 2025). This usage is mathematically precise but unrelated to polarity suppression.

For encyclopedia practice, the implication is straightforward: the unqualified acronym “RPS” should not be treated as self-explanatory. In the present topic, the phrase “Random Polarity Suppression” is viable only as an explicitly defined interpretive label, not as a term already stabilized by acronym convention across arXiv literature.

6. Significance, applications, and limits of the concept

The scientific significance of interpretive RPS is domain-specific. In the stellar-jet framework, the relevance lies in reconstructing the magnetic and jet variability history of young stars from planetary architectures (Namouni, 2012). The paper states that periodic and random polarity reversals leave distinct dynamical signatures, including different inclination growth, migration behavior, and relative inclination structure in multiplanet systems. Applying the mechanism to the solar system, it argues that the planet–jet variability resonance with periodic polarity reversal momentum loss is a possible origin for the hitherto unexplained inclination of Jupiter’s orbit by $\tau$6 deg. with respect to the Sun’s equator. Random reversal is disfavored because the observed small relative inclination of Jupiter and Saturn $\tau$7 is not naturally matched.

In the III-nitride context, the significance is technological as well as structural (Zhang et al., 2022). N-polar devices are attractive for low-resistance ohmic contacts, natural back-barrier formation, stronger carrier confinement, and improved scaling, but polarity disorder during nucleation degrades the interfaces needed for device-grade material. By transferring the HT off-axis AlN nucleation recipe into AlGaN/GaN/AlN heterostructures, the paper reports step-flow growth of the HEMT structure, atomically sharp interfaces, representative AlGaN top-surface RMS roughness $\tau$8 nm over $\tau$9, later optimized to $4H$00 nm, $4H$01DEG carrier density up to $4H$02, and anisotropic room-temperature electron mobility $4H$03. These numbers are presented as evidence that polarity-controlled material is viable for device structures.

The limits of the concept are equally important. There is no general-purpose “Random Polarity Suppression” formalism in the supplied corpus. The orbital paper does not introduce a named suppression mechanism and, in one major regime, random reversals enhance rather than suppress excitation. The materials paper demonstrates polarity-control by inversion domain suppression, but it does so for a specific epitaxial system: high-temperature AlN nucleation on $4H$04 off-axis C-face $4H$05-SiC under sufficiently low Al supersaturation. A plausible implication is that “Random Polarity Suppression” is best reserved for carefully delimited contexts in which the meaning of “random,” “polarity,” and “suppression” is explicitly specified.

Taken together, the corpus supports a narrow and technically disciplined usage. In orbital dynamics, RPS can only mean a relative suppression of resonance-crossing excitation by random polarity reversals. In III-nitride epitaxy, it can denote suppression of stochastic or unintended local polarity inversion by controlling supersaturation, substrate misorientation, and growth mode. Outside those contexts, the same acronym already names unrelated frameworks, and any encyclopedia treatment must foreground that ambiguity rather than conceal it.