arXiv subjects

Saurav Roy

Publications and source records attributed to Saurav Roy.

21 records · Page 2Linked to original sources

arXiv2020

Low Temperature Homoepitaxy Of (010) $β$-Ga$_2$O$_3$ By Metalorganic Vapor Phase Epitaxy : Expanding The Growth Window

In this work, we report on the growth of high-mobility $β$-Ga$_2$O$_3$ homoepitaxial thin films grown at a temperature much lower than the conventional growth temperature window for metalorganic vapor phase epitaxy. Low-temperature $β$-Ga$_2$O$_3$ thin films grown at 600$^{\circ}$C on Fe-doped (010) bulk substrates exhibits remarkable crystalline quality which is evident from the measured room temperature Hall mobility of 186 cm$^2$/Vs for the unintentionally doped films. N-type doping is achieved by using Si as a dopant and controllable doping in the range of 2$\times$10$^{16}$ - 2$\times$10$^{19}$ cm$^{-3}$ is studied. Si incorporation and activation is studied by comparing silicon concentration from secondary ion mass spectroscopy (SIMS) and electron concentration from temperature-dependent Hall measurements. The films exhibit high purity (low C and H concentrations) with a very low concentration of compensating acceptors (2$\times$10$^{15}$ cm$^{-3}$) even at this growth temperature. Additionally, abrupt doping profile with forward decay of $\sim$ 5nm/dec (10 times improvement compared to what is observed for thin films grown at 810$^{\circ}$C) is demonstrated by growing at a lower temperature.

physics.app-ph↗

arXiv2020

Design of a $β$-Ga$_2$O$_3$ Schottky Barrier Diode With p-type III-Nitride Guard Ring for Enhanced Breakdown

This work presents the electrostatic analysis of a novel Ga$_2$O$_3$ vertical Schottky diode with three different guard ring configurations to reduce the peak electric field at the metal edges. Highly doped p-type GaN, p-type nonpolar AlGaN and polarization doped graded p-AlGaN are simulated and analyzed as the guard ring material, which forms a heterojunction with the Ga$_2$O$_3$ drift layer. Guard ring with non-polar graded p-AlGaN with a bandgap larger than Ga$_2$O$_3$ is found to show the best performance in terms of screening the electric field at the metal edges. The proposed guard ring configuration is also compared with a reported Ga$_2$O$_3$ Schottky diode with no guard ring and a structure with a high resistive Nitrogen-doped guard ring. The optimized design is predicted to have breakdown voltage as high as 5.3 kV and a specific on-resistance of 3.55 m$Ω$-cm$^2$ which leads to an excellent power figure of merit of 7.91 GW/cm$^2$.

physics.app-ph↗

arXiv2020

Schottky Barrier Height Engineering In $β$-Ga$_2$O$_3$ Using SiO$_2$ Interlayer Dielectric

This paper reports on the modulation of Schottky barrier heights (SBH) on three different orientations of $β$-Ga$_2$O$_3$ by insertion of an ultra-thin SiO$_2$ dielectric interlayer at the metal-semiconductor junction, which can potentially lower the Fermi-level pinning (FLP) effect due to metal-induced gap states (MIGS). Pt and Ni metal-semiconductor (MS) and metal-interlayer-semiconductor (MIS) Schottky barrier diodes were fabricated on bulk n-type doped $β$-Ga$_2$O$_3$ single crystal substrates along the (010), (-201) and (100) orientations and were characterized by room temperature current-voltage (I-V) and capacitance-voltage (C-V) measurements. Pt MIS diodes exhibited 0.53 eV and 0.37 eV increment in SBH along the (010) and (-201) orientations respectively as compared to their respective MS counterparts. The highest SBH of 1.81 eV was achieved on the (010)-oriented MIS SBD using Pt metal. The MIS SBDs on (100)-oriented substrates exhibited a dramatic increment ($>$1.5$\times$) in SBH as well as reduction in reverse leakage current. The use of thin dielectric interlayers can be an efficient experimental method to modulate SBH of metal/Ga$_2$O$_3$ junctions.

physics.app-ph↗