arXiv subjects

Advait Gilankar

Publications and source records attributed to Advait Gilankar.

7 recordsLinked to original sources

arXiv2026

$\beta-(Al_{0.19} Ga_{0.81})_2 O_3/Ga_2 O_3$ Modulation-Doped Field-Effect Transistors with $>$ 6 kV Breakdown

$\beta-(Al_{0.19} Ga_{0.81})_2 O_3/Ga_2 O_3$ modulation-doped field-effect transistors (MODFETs) incorporating a high-quality Al2O3 gate dielectric and SiNx passivation are demonstrated for high-voltage operation. The devices exhibited a maximum drain current of 54 mA/mm, an on-resistance of 149 Ohm.mm, a minimum subthreshold slope of 94 mV/dec, and an ION/IOFF ratio exceeding $10^8$. Three-terminal breakdown measurements performed in Flourinert demonstrated a breakdown voltage that increased with gate-drain spacing, reaching 6.6 kV for a device with LGD = 28 microns. The corresponding average lateral electric field approached 2.4 MV/cm, while a power figure of merit of 222 MW/cm2 was achieved. To the best of the authors knowledge, the demonstrated breakdown voltage represents the highest reported value for a $\beta-(Al_x Ga_{1-x})_2 O_3/Ga_2 O_3$ MODFET and highlights the potential of modulation-doped $\beta$-Ga2O3 heterostructures for next-generation multi-kV power devices.

cond-mat.mtrl-sci↗

arXiv2026

Temperature Dependent Characteristics of Quasi-vertical AlN Schottky Diodes on Bulk AlN Substrate

We report on the fabrication and temperature-dependent characterization of MOCVD-grown quasi-vertical AlN Schottky barrier diodes (SBDs) on bulk AlN substrates. The SBDs exhibited high current densities exceeding 2 kA/cm2 at 10 V, with a turn-on voltage of ~3.0 V (at 1 A/cm^2) and an on/off ratio >10^9 at room temperature. Stable rectifying operation was maintained up to 300 C (the highest measured temperature), with a pronounced increase in current density at elevated temperatures due to thermally activated carrier transport, accompanied by an increase in extracted Schottky barrier height and a reduction in ideality factor. Capacitance voltage measurements showed strong temperature dependence due to the deep donor nature of Si in AlN, resulting in an increase in the net donor concentration (ND-NA) from ~5x10^17 cm-3 at 300 K to ~1x10^18 cm-3 at 373 K. Temperature-dependent reverse-bias characteristics were consistent with Poole-Frenkel emission as the dominant leakage mechanism, with an estimated trap energy of ~0.34 eV. Characterization using transmission electron microscopy and energy-dispersive X-ray spectroscopy revealed a ~5 nm AlNxOy interfacial layer at the metal/semiconductor junction, which likely influences both forward and reverse transport. These results provide insight into carrier transport, leakage mechanisms, interface chemistry, and high-temperature characteristics, and guidance for the future development of high-performance AlN power devices.

physics.app-ph↗

arXiv2025

Beta-Ga2O3 Sub-Micron FinFETs with Si Delta-Doped Channel Modulating Charge Density Above 3x10^13 cm^-2

This letter reports on the design and demonstration of high-performance Beta-Ga2O3 FinFETs utilizing MOCVD-grown Si delta-doped channels to achieve enhanced carrier transport and electrostatic control. A record high sheet charge density of 3.3x10^13 cm^-2 was modulated using 100 nm fin channels, delivering a peak drain current of 410 mA/mm and a peak transconductance of 60 mS/mm. The FinFET architecture enables strong gate modulation, achieving a high Ion/Ioff ratio between 10^8 and 10^9. A low contact resistance of 0.42 ohm.mm was achieved to the Si delta-doped channel using MOCVD contact regrowth. Small-signal RF characterization revealed a current-gain cutoff frequency (fT) of 3.8 GHz and a maximum oscillation frequency (fMAX) of 2.1 GHz for a 0.8-micrometer gate length. These results demonstrate the efficacy of combining precision delta-doping with a 3D FinFET geometry for high-frequency Beta-Ga2O3 electronics, establishing a platform for future RF and high-power applications

physics.app-ph↗

arXiv2025

Demonstration of KV-Class \b{eta}-Ga2O3 Trench Junction Barrier Schottky Diodes with SpaceModulated Junction Termination Extension

In this work, we report on the design and fabrication of p-NiO/Ga2O3 trench junction barrier schottky diodes (JBSD) integrated with space-modulated junction termination extension (SM-JTE) and compare the performance with planar Ni/Ga2O3 schottky diodes (SBDs) and p-NiO/Ga2O3 heterojunction diodes (HJDs). The JBSDs achieved breakdown voltages exceeding 1.8 kV along with low leakage currents (<10-2 A/cm2), while displaying low turn on voltage (VON) of ~1V, which is similar to that of planar Ni/Ga2O3 SBDs. The fabricated devices showed excellent forward characteristics with low differential on-resistance (Ron,sp) ranging from 4-10.5 m{\Omega}-cm2, for fin width between 0.6- 1.25 microns. Best performing device with fin width of 0.85{\mu}m showed a unipolar figure of merit (FOM) of ~0.7GW/cm2. This work showcases the benefits of trench JBS design along with SM-JTE edge-termination for efficient high-performance kilovolt-class \b{eta}- Ga2O3 diodes.

physics.app-ph↗

arXiv2024

>3kV NiO/Ga2O3 Heterojunction Diodes with Space-Modulated Junction Termination Extension and Sub-1V Turn-on

This work demonstrates high-performance vertical NiO/Ga2O3 heterojunction diodes (HJDs) with a 2-step space-modulated junction termination extension. Distinct from the current state-of-the-art Ga2O3 HJDs, we achieve breakdown voltage exceeding 3 kV with a low turn on voltage (VON) of 0.8V, estimated at a forward current density (IF) of 1 A-cm-2. The measured devices exhibit excellent turn-on characteristics achieving 100 A-cm-2 current density at a forward bias of 1.5V along with a low differential specific on-resistance (Ron,sp) of 4.4 m{\Omega}-cm2. The SM-JTE was realized using concentric NiO rings with varying widths and spacing that approximates a gradual reduction in JTE charge. The unipolar figure of merit (FOM) calculated exceeds 2 GW-cm2 and is among the best reported for devices with a sub-1V turn-on. The fabricated devices also displayed minimal change in forward I-V characteristics post reverse bias stress of 3 kV applied during breakdown voltage testing.

physics.app-ph↗

arXiv2024

In-situ Patterned Damage-Free Etching of 3-Dimensional Structures in \b{eta}-Ga2O3 using Triethylgallium

In this work, we report on the anisotropic etching characteristics of \b{eta}-Ga2O3 using triethylgallium (TEGa) performed in-situ within an MOCVD chamber. At sufficiently high substrate temperature, TEGa can act as a strong etchant for \b{eta}-Ga2O3 utilizing the suboxide reaction between Ga and Ga2O3. We observe that due to monoclinic crystal structure of \b{eta}-Ga2O3, TEGa etching on both (010) and (001) substrates is highly anisotropic in nature, both in terms of sidewall roughness and lateral etch rate. Smooth sidewalls are only obtained along crystal orientations that minimize sidewall surface energy. Utilizing this technique we also demonstrate deep sub-micron fins with smooth sidewalls and high aspect ratios. Furthermore, we also demonstrate the damage free nature of TEGa etching by fabricating Schottky diodes on the etched surface which display no change in net donor concentration.

cond-mat.mtrl-sci↗

arXiv2021

Investigations on the improved cycling stability of Kazakhstanite phase Fe-V-O layered oxide by using superconcentrated electrolytes: Generalized solubility limit approach (Part I)

In this article, we address the issue of vanadium dissolution pertinent in the layered Fe5V15O39(OH)9.9H2O using the solubility limit approach. This layered oxide is prepared via a low-cost solution phase synthesis route and crystallizes in the Kazakhstanite phase (Space Group: C2/m), confirmed using selected area electron diffraction and x-ray diffraction.The layered oxide exhibits the 2 electron redox reaction of vanadium (V5+ to V3+) along with the 1 electron redox reaction of iron within the voltage window of 1.5-3.8V. This results in a high specific capacity of ~350mAhg-1 which can be extracted from this material. However, the transition from V4+ to V3+ is identified to initiate a dissolution process at ~2.5V, resulting in a loss of active material and poor cycling stability. The vanadium dissolution is found to be arrested by switching to a superconcentrated electrolyte, wherein the amount of 'free' solvent is low. An electrolyte, consisting of seven molar lithium bis(trifluoromethanesulfonyl)imide in 1,3-Dioxolane: 1,2-Dimethoxyethane = 1:1 (v:v), is found to be suitable in providing the best cycling stability amongst the other compositions tested. The electrochemical characteristics of the passivation layers formed over lithium foil are mathematically modeled to indicate the preference of superconcentrated electrolytes over relatively dilute ones.

cond-mat.mtrl-sci↗