Schottky Barrier Height Engineering inβ-Ga2O3Using SiO2Interlayer Dielectric

Kelvin G Lynn,Muad Saleh,Michael A Scarpulla,Arkka Bhattacharyya,Saurav Roy,Sriram Krishnamoorthy,Praneeth Ranga

doi:10.1109/jeds.2020.2974260

Abstract

This paper reports on the modulation of Schottky barrier heights (SBH) on three different orientations of $\beta$-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 $\beta$-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.

Highlights

Beta-Ga2O3 is a transparent conducting oxide which has emerged as a promising candidate for generation power electronic devices largely due to its wide band gap (Eg ∼ 4.6 - 4.9 eV) [1], [2]
The MIS SBDs showed an increased forward voltage compared to the MS diodes, along all the orientations as expected, indicating that the Schottky barrier heights (SBH) of MIS diodes might be higher than their respective bare metal MS counterparts, in addition to the blocking of model which can be expressed as
In this work, we demonstrate the enhancement of Schottky barrier heights on three orientations of β-Ga2O3 substrates by insertion of ultra-thin SiO2 interfacial layer at the MS junction

Summary

INTRODUCTION

Beta-Ga2O3 is a transparent conducting oxide which has emerged as a promising candidate for generation power electronic devices largely due to its wide band gap (Eg ∼ 4.6 - 4.9 eV) [1], [2]. Study on (100) and (001) β-Ga2O3 is rather sparse and till date very low barrier heights have been reported for (100) β-Ga2O3 [15], [17], [19], [20], [23], [25], [26], [30] We investigate the modulation of Schottky barrier height on different orientations of β-Ga2O3 single crystal substrates with the insertion of ultra-thin SiO2 dielectric layer at the metal-semiconductor interface

DEVICE FABRICATION AND CHARACTERIZATION

RESULTS AND DISCUSSIONS

CONCLUSION