Formation of a p-n junction on the GaAs-surface by an Ar+ ion beam

TL;DR

This study demonstrates that Ar+ ion beam irradiation can convert the surface of n-GaAs into p-type, enabling local p-n junction formation through defect-induced conductivity change, as revealed by photoelectron spectroscopy.

Contribution

It provides direct spectroscopic evidence of n-to-p conversion and local p-n junction formation on GaAs surfaces via ion beam modification, a novel approach in semiconductor surface engineering.

Findings

Surface conductivity type changes from n to p after ion irradiation.

Core-level and valence band shifts indicate bandgap-level modifications.

Local p-n junctions can be formed within the ion-beam spot.

Abstract

The core-level and valence band electronic structure of the well-defined near-surface layer of n-GaAs (100) has been studied by synchrotron-based high-resolution photoelectron spectroscopy before and after modification of the layer by an Ar+ ion beam in the 1.5 - 2.5 keV energy range. Conversion of the conductivity type from n into p has been revealed in the irradiated layer several nm thick. The effect manifests itself in shifts of the core-levels and valence band edge by the value comparable to the bandgap width. Transformation on the conductivity type has been assumed to be caused by Ga-antisite point defects generated by ion bombardment. The possibility of local formation of a p-n nanojunction within the ion-beam spot has been shown.