Simultaneously monitoring Ga adsorption and desorption kinetics on GaN(0001) using four in situ techniques

TL;DR

This study employs four in situ techniques simultaneously to analyze Ga adsorption and desorption kinetics on GaN(0001), providing a comprehensive understanding of surface processes with a unified kinetic model.

Contribution

It introduces a combined in situ measurement approach and a unified kinetic model to quantitatively analyze Ga surface kinetics on GaN(0001).

Findings

All four techniques' signals are quantitatively consistent with the kinetic model.

Desorption activation energy is determined as 2.87 eV.

The model accurately describes surface coverage effects across regimes.

Abstract

We present a systematic investigation of Ga adsorption and desorption kinetics on the wurtzite GaN(0001) surface using four in situ techniques operated simultaneously: reflection high-energy electron diffraction, laser reflectometry, line-of-sight quadrupole mass spectrometry, and optical pyrometry. Flux- and temperature-dependent experiments are performed for Ga coverages ranging from the submonolayer to the droplet regime. Despite their distinct transient responses, the signals from all four techniques and their trends with surface coverage are quantitatively reproduced by a unified kinetic model of Ga adsorption, diffusion, and desorption. An Arrhenius analysis of the Ga adlayer desorption yields an activation energy of (2.87 $\pm$ 0.04) eV.