First-principle approach based bandgap engineering for cubic boron nitride doped with group IIA elements

Yubo Li,Shijie Zhan,Jikui Luo,Pengtao Wang,Xiaozhi Wang,Fei Hua,Hangsheng Yang

doi:10.1063/1.5019955

Abstract

Electronic properties of cubic boron nitride (c-BN) doped with group IIA elements were systematically investigated using the first principle calculation based on density functional theory. The electronic bandgap of c-BN was found to be narrowed when the impurity atom substituted either the B (IIA→B) or the N (IIA→N) atom. For IIA→B, a shallow accept level degenerated into valence band (VB); while for IIA→N, a shallow donor level degenerated conduction band (CB). In the cases of IIBe→N and IIMg→N, deep donor levels were also induced. Moreover, a zigzag bandgap narrowing pattern was found, which is in consistent with the variation pattern of dopants’ radius of electron occupied outer s-orbital. From the view of formation energy, the substitution of B atom under N-rich conditions and the substitution of N atom under B-rich conditions were energetically favored. Our simulation results suggested that Mg and Ca are good candidates for p-type dopants, and Ca is the best candidate for n-type dopant.

Highlights

It is worth noting that deep impurity levels, which were detrimental for the electronic property of cubic boron nitride (c-BN), could be induced in the cases of IIBe→N and IIMg→N
The shallow impurity level induced by IIBe→B and deep impurity levels induced by IIBe→N found in this paper are in consistent with the results reported by Ref. 32
The first principle calculation has been performed to investigate the relationship of bandgap of doped c-BN using IIA group elements as impurity

Summary

Introduction

With the largest bandgap (6.2-6.4eV) among group IIIA nitrides, cubic boron nitride (c-BN) shows excellent properties like ultra-high hardness, high thermal conductivity, high melting temperature and wonderful stability,[1,2,3] it is a promising material for high temperature devices, high power transistors and photoelectronic devices as it can withstand high temperature without deterioration of its performances.[4,5,6] For electronic and optical device applications, it is necessary to adjust electrical conductivity and bandgap of c-BN, which could be achieved through doping of impurity atoms.Doping of c-BN has been studied using Be, C, Mg, Si, S, IIIA and some rare earth elements (Er, Sm, La, Eu, V) as impurity atoms.[7,8,9,10,11,12,13,14,15,16,17,18,19,20] And it was found that Be, Mg or Zn doped c-BN achieved typically p-type semiconductors, while S or Si doped c-BN was reported to obtain n-type semiconductors.[7,11,12] Gubanov found that the impurity levels induced by Be were strongly delocalized, and the impurity levels induced by Mg were localized, which suggested that Be-induced states could be more effective than those by Mg-induced for p-type doping of c-BN.[14]While these research developments are encouraging, there is still a lack of systematical research and comparison on c-BN doping with different impurity atoms, which is important to understand the mechanism and to obtain detail information of c-BN doping. Doping of c-BN has been studied using Be, C, Mg, Si, S, IIIA and some rare earth elements (Er, Sm, La, Eu, V) as impurity atoms.[7,8,9,10,11,12,13,14,15,16,17,18,19,20] And it was found that Be, Mg or Zn doped c-BN achieved typically p-type semiconductors, while S or Si doped c-BN was reported to obtain n-type semiconductors.[7,11,12] Gubanov found that the impurity levels induced by Be were strongly delocalized, and the impurity levels induced by Mg were localized, which suggested that Be-induced states could be more effective than those by Mg-induced for p-type doping of c-BN.[14].

Methods

Results

Conclusion