Structures built by steps of evaporated crystal surface Monte Carlo simulations and experimental data for GaN epi layers

TL;DR

This study combines Monte Carlo simulations and experimental data to analyze how different step structures form on GaN surfaces during high-temperature annealing, revealing temperature and time-dependent pattern evolution.

Contribution

It introduces a detailed simulation approach to predict step pattern formation on GaN surfaces, correlating with experimental observations.

Findings

Short evaporation times produce rough steps.

Longer evaporation times lead to curly step patterns.

Extended annealing causes step bunching and waviness.

Abstract

We present Monte Carlo simulation data obtained for the annealed surface GaN(0001) and compare them with the experimental data. High temperature particle evaporation is a part of substrate preparation processes before epitaxy. The ideal surface ordering expected after such heating is a pattern of parallel, equally distanced steps. It appears however, that different types of step structures emerge at high temperatures. We show how the creation of characteristic patterns depends on the temperature and the annealing time. The first pattern is created for a very short evaporation time and consists of rough steps. The second pattern built by curly steps is characteristic for longer evaporation times and lower temperatures. The third pattern, in which steps merge together creating bunches of steps happens for the long enough time. At higher temperatures, bunches of steps bend into the wavy-like structures.