Regulation of Hole Concentration and Mobility and First-Principle Analysis of Mg-Doping in InGaN Grown by MOCVD.

Lian Zhang,Xiaodong Tong,Shiyong Zhang,Zhe Liu,Fengxiang Chen,Jianxing Xu,Yun Zhang,Zhe Cheng,Rong Wang

doi:10.3390/ma14185339

Abstract

This work studied the regulation of hole concentration and mobility in p-InGaN layers grown by metalorganic chemical vapor deposition (MOCVD) under an N-rich environment. By adjusting the growth temperature, the hole concentration can be controlled between 6 × 1017/cm3 and 3 × 1019/cm3 with adjustable hole mobility from 3 to 16 cm2/V.s. These p-InGaN layers can meet different requirements of devices for hole concentration and mobility. First-principles defect calculations indicate that the p-type doping of InGaN at the N-rich limiting condition mainly originated from Mg substituting In (MgIn). In contrast with the compensation of nitrogen vacancy in p-type InGaN grown in a Ga-rich environment, the holes in p-type InGaN grown in an N-rich environment were mainly compensated by interstitial Mg (Mgi), which has very low formation energy.

Highlights

Accepted: 13 September 2021InGaN alloys are attractive semiconductor materials due to their tunable bandgap energy (Eg ) range from 0.65 to 3.4 eV
100 nm were reported in solar cells [7] and heterojunction bipolar transistors (HBTs) [8] as the hole-injection and p-type conduction layers
With a hole concentration up to 3 × 1019 cm−3 was grown on a GaN substrate by plasmaassisted molecular beam epitaxy (MBE) (PA-MBE) [14]

Summary

Introduction

Accepted: 13 September 2021InGaN alloys are attractive semiconductor materials due to their tunable bandgap energy (Eg ) range from 0.65 to 3.4 eV. Due to the high absorption coefficient (~105 cm−1 ) and high radiation resistance [4], thick intrinsic InGaN layers are prospective candidates for solar cells [5]. The valance band maximum (VBM) of InGaN alloys is higher than that of GaN, which reduces the active energy of Mg and contributes to a high hole concentration in gallium nitrides. Many scholars focused on improving the crystal quality of p-type InGaN layers to obtain a large hole concentration and maintain high hole mobility [9,10,11,12]. A p-type In0.18 Ga0.82 N with a hole concentration up to 3 × 1019 cm−3 was grown on a GaN substrate by plasmaassisted MBE (PA-MBE) [14]. MOCVD was used to grow a p-type In0.22 Ga0.78 N layer

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Conclusion