Two-dimensional electron gas at wurtzite–zinc-blende InP interfaces induced by modulation doping

Irene Geijselaers,Kimberly A Dick,Mats-Erik Pistol,Sebastian Lehmann

doi:10.1063/5.0009818

Irene Geijselaers, Kimberly A Dick + Show 2 more

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https://doi.org/10.1063/5.0009818

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Journal: Applied Physics Letters	Publication Date: Jun 8, 2020
Citations: 9	License type: cc-by

Affiliation: Lund University

Abstract

The quality, such as long-range correlation and mobility, of a two-dimensional electron gas (2DEG) is limited by, among other factors, interface roughness, which is inherent to the use of compositional heterostructures. Polytypic heterostructures have atomically sharp interfaces and minimal strain, decreasing the interface roughness, which may increase the mobility and long-range correlation of 2DEGs. In this work, we show the formation of a 2DEG at the wurtzite–zinc blende interface in partially n-type-doped InP nanowires using power-dependent photoluminescence. We additionally determined the wurtzite–zinc blende InP valence band offset to be 35 meV &lt;ΔEv&lt; 70 meV. Our results may enable the study of electron gases at interfaces, which are atomically flat over large areas.

Highlights

A possible solution to the interface roughness issue is the use of polytypic interfaces: interfaces between two crystal structures made from the identical compounds
It has been shown that a wz–zb indium phosphide (InP) interface shows a type-II band alignment, with the wz-InP bandgap being shifted to higher energy by the valence band offset (DEv)
Note that in this system, the polytype heterostructure is oriented in the axial direction, and so the 2DEG at the wz–zb InP interface is free to move only in the radial direction

Summary

Introduction

A possible solution to the interface roughness issue is the use of polytypic interfaces: interfaces between two crystal structures made from the identical compounds. Polytypic heterostructures have atomically sharp interfaces and minimal strain, decreasing the interface roughness, which may increase the mobility and long-range correlation of 2DEGs. In this work, we show the formation of a 2DEG at the wurtzite–zinc blende interface in partially n-type-doped InP nanowires using power-dependent photoluminescence. It has been shown that a wz–zb InP interface shows a type-II (staggered) band alignment, with the wz-InP bandgap being shifted to higher energy by the valence band offset (DEv).16 This DEv has been calculated to be between 45 meV and 80 meV,16–18 with no experimental verification so far.

Results

Conclusion