Anomalous Mn depth profiles for GaMnAs/GaAs(001) thin films grown by molecular beam epitaxy

TL;DR

This study investigates Mn depth profiles in GaMnAs thin films grown by molecular beam epitaxy at different substrate temperatures, revealing uniform distribution at low temperatures and anomalous peaks at higher temperatures when Mn exceeds solubility limits.

Contribution

It provides new insights into the Mn distribution behavior in GaMnAs films grown at different temperatures, highlighting anomalous profiles below the solubility limit.

Findings

Uniform Mn distribution at 250°C

Anomalous peaks in profiles above solubility limit at 580°C

Temperature-dependent Fermi function fits high concentration profiles

Abstract

Mn concentration depth profiles in Mn-doped GaAs thin films grown at substrate temperatures of 580 and 250 {\deg}C using various Mn cell temperatures have been investigated with dynamic secondary ion mass spectrometry and Auger electron spectroscopy. When the samples are grown at a low substrate temperature of 250 {\deg}C, the Mn distributes uniformly. For the samples grown at a high substrate temperature of 580 {\deg}C, the concentration depth profiles are easily fitted with a temperature-dependent Fermi function only if the Mn concentration is above the solubility limit. However, when the Mn concentration is below the solubility limit, unexpected peaks are observed in the concentration depth profiles.