Undoped β-Ga₂O₃ Layer Thickness Effect on the Performance of MOSFETs Grown on a Sapphire Substrate

Abstract

β-Ga 2 O 3 metal-oxide-semiconductor field-effect transistors (MOSFETs) with various unintentionally doped (UID) layer thicknesses (50, 100, and 200 nm) of (2̅ 01) beneath the Si tetraethoxysilane (TEOS)-doped film were grown by metal− organic chemical vapor deposition on a (0001) sapphire substrate. The UID layer thickness causes the MOSFET turn-on current to increase from 1.7 to 700 μA/mm, R ON to decrease from 1.13 MΩ•mm to 3.8 kΩ•mm, and breakdown voltage to decrease from 910 to 240 V. Through X-ray photoelectron spectroscopy (XPS), we ascribe this increased turn-on current and reduced breakdown voltage to oxygen vacancies. KEYWORDS: β-Ga 2 O 3 , metal-oxide-semiconductor field-effect transistors (MOSFETs), unintentionally doped (UID) layers, tetraethoxysilane (TEOS), metal−organic chemical vapor deposition, X-ray photoelectron spectroscopy (XPS)

A 2.8 kV Breakdown Voltage α-Ga2O3 MOSFET with Hybrid Schottky Drain Contact

“…suppressing the peak E-field at the UID layer might contribute to the breakdown characteristics of the α-Ga2O3 MOSFET [38]. The simulation results foresee enhanced breakdown characteristic from the HSD device, as demonstrated in the following section.…”

“…Additionally, the HSD device exhibits a lower peak E-field at the corresponding region of the α-Ga 2 O 3 /UID interface. Considering the undoped α-Ga 2 O 3 buffer layer, which is an unintentionally n-doped layer due to the presence of oxygen vacancies, suppressing the peak E-field at the UID layer might contribute to the breakdown characteristics of the α-Ga 2 O 3 MOSFET [ 38 ]. The simulation results foresee enhanced breakdown characteristic from the HSD device, as demonstrated in the following section.…”

“…The LFOMs of the OD and HSD devices are 2.4 and 7.8 MW/cm 2 , respectively. The electrical characteristics of the heteroepitaxial Ga 2 O 3 MOSFETs are summarized in Table 1 [ 18 , 38 , 39 , 40 , 41 , 42 ]. Some parameters are missing because they were not discussed in the published results.…”

“…Our results show that the proposed HSD electrode can be promising with further advanced device structures toward α-Ga2O3 power devices. MOCVD [39] κ-~10 8 2.43 --390 MOCVD [40] β-~10 11 11.4 --400 MOCVD [38] β-~10 5 150 3.8 240 MOCVD [41] ε---19 ----HVPE [42] β-~10 6 5.3 88.9 155 HVPE [18] α-~10 6…”

“…Phase On/Off µFE (cm 2 /V-s) Ron (kΩ-mm) BV (V) MOCVD [39] κ-~10 8 2.43 --390 MOCVD [40] β-~10 11 11.4 --400 MOCVD [38] β-~10 5 150 3.8 240 MOCVD [41] ε---19 ----HVPE [42] β-~10 6 5.3 88.9 155 HVPE [18] α-~10 6…”