Towards P-Type Conduction in Hexagonal Boron Nitride: Doping Study and Electrical Measurements Analysis of hBN/AlGaN Heterojunctions

Adama Mballo,Yacine Halfaya,Soufiane Karrakchou,Paul L Voss,Jean Paul Salvestrini,Abdallah Ougazzaden,Simon Gautier,Suresh Sundaram,Ali Ahaitouf,Phuong Vuong,Ashutosh Srivastava

doi:10.3390/nano11010211

Abstract

Reliable p-doped hexagonal boron nitride (h-BN) could enable wide bandgap optoelectronic devices such as deep ultra-violet light emitting diodes (UV LEDs), solar blind photodiodes and neutron detectors. We report the study of Mg in h-BN layers as well as Mg h-BN/AlGaN heterostructures. Mg incorporation in h-BN was studied under different biscyclopentadienyl-magnesium (Cp2Mg) molar flow rates. 2θ-ω x-ray diffraction scans clearly evidence a single peak, corresponding to the (002) reflection plane of h-BN with a full-width half maximum increasing with Mg incorporation in h-BN. For a large range of Cp2Mg molar flow rates, the surface of Mg doped h-BN layers exhibited characteristic pleats, confirming that Mg doped h-BN remains layered. Secondary ion mass spectrometry analysis showed Mg incorporation, up to 4 × 1018 /cm3 in h-BN. Electrical conductivity of Mg h-BN increased with increased Mg-doping. Heterostructures of Mg h-BN grown on n-type Al rich AlGaN (58% Al content) were made with the intent of forming a p-n heterojunction. The I-V characteristics revealed rectifying behavior for temperatures from 123 to 423 K. Under ultraviolet illumination, photocurrent was generated, as is typical for p-n diodes. C-V measurements evidence a built-in potential of 3.89 V. These encouraging results can indicate p-type behavior, opening a pathway for a new class of wide bandgap p-type layers.

Highlights

Control of doping and conductivity is of critical importance for fabrication of semiconductor-based devices
We report an experimental study of the electrical behavior of Mg incorporation in hexagonal boron nitride (h-BN)
Similar wrinkles were observed on the B and C h-BN samples (Figure 1b,c)

Summary

Introduction

Control of doping and conductivity is of critical importance for fabrication of semiconductor-based devices. LEDs, the p-type doping of Al rich AlGaN with Mg is extremely challenging because of its large ionization energy in AlN (~500 meV) [1,2,3,4,5]. An alternate wide bandgap material with appropriate p-type doping is highly desired. Hexagonal boron nitride (h-BN) is a promising material for p-type wide bandgap nitride such as UV-LEDs [6,7,8,9] and UV detectors [10,11,12]. It was reported that the p doping of h-BN can be achieved using Zn, Be and Mg as dopants [13,14,15,16,17,18,19,20].

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