1. Reconstruction of the Surface of GaAs Film
MatSE390 Project
Reconstruction of the Surface of GaAs Film
Yunfeng Shi

2. Introduction
Thin-film growth on a GaAs(001) surface, either homoepitaxial or heteroepitaxial, has a great technological importance when developing optoelectronic devices. In order to get high quality of film, we must control the surface reconstruction. This is called surface-structure-controlled epitaxy.
RHEED,SEM
FLUX RATIO
TEMPERATURE
FILM GROWTH
Feed Back

3. Algorithm
Monte Carlo Method and Metropolis Algorithm are used here. The top-most layer is our interest. Since in experiments, there will be two types of surface, Ga-rich surface and As-rich surface, while they have different characteristics. The first few layers near surface are also allowed to move. Lattice Model is also used to fast the speed.
A modified Tersoff Potential is used:

4. Results
From normal Monte Carlo method, we can find that As-rich acts quite differently compared to Ga-rich surface. Ga atoms are much more active than As atom. We can see from below:At 3000k, After runs, As atoms mostly stay at the original position, while Ga atoms moves a lot.

5. Single As atom Potential Contour
Single Ga atom Potential Contour

6. POTENTIAL CURVES

7. RECONSTRUCTION OF GA-RICH SURFACE
Starting postition
Final position
Analysis:
9/25 type

8. Conclusion
Surface reconstruction can be got by Monte Carlo method for the GaAs film. It can be faster if using lattice model. We can also see the different behaviors of Ga and As atoms on surface.