Investigation of n-type dilute magnetic semiconductor property observed in amorphous AlNO alloy thin film incorporated with dilute nitrogen at 300K

TL;DR

This study reports the synthesis and characterization of an amorphous AlNO alloy thin film that exhibits n-type dilute magnetic semiconductor properties at room temperature, combining experimental and theoretical analyses.

Contribution

It introduces a novel method to create n-type DMS at room temperature by nitrogen interstitial incorporation in Al2O3, supported by experimental and DFT calculations.

Findings

The film shows low resistivity and high carrier mobility at 300K.

Nitrogen prefers interstitial sites, inducing magnetic properties.

The study provides insights into room-temperature n-type DMS fabrication.

Abstract

In the present work, a thin film was deposited on quartz substrate by reactive RF magnetron sputtering of high purity (99.999%) aluminium target using ultra-high pure (Ar + N2) gas mixture. The percentage ratio of Ar and N2 in the gas mixture was 95% and 5%, respectively. Chemical characterization using x-ray photoelectron spectroscopy (XPS) and energy-dispersive xray (EDX) spectroscopy reveals that in the presence of dilute nitrogen, Al prefers to react with residual oxygen to form Al2O3 while the nitrogen is incorporated in it. The stoichiometry of bulk film is Al2N0.38O3.1. Magnetic and electrical properties measurement shows that the film exhibits ntype dilute magnetic semiconductor (DMS) property at 300K. The film has low electrical resistivity of 6.3 {\Omega}-cm and high carrier mobility of 5.7*106 cm2V-1s-1 at 300K. A density functional theory (DFT) calculation was performed to investigate the origin of observed magnetism in the film. From first-principles calculation based on DFT, it is found that for thermodynamic stability dilute nitrogen incorporated in Al2O3 preferred to sit at the interstitial site, which is responsible for observed magnetic property. Present study reported here provides a new insight to prepare rarely observed n-type DMS at room temperature by incorporating nitrogen interstitials in Al2O3, which is desirable for potential application in the field of spintronics.