ALE GaAs生长过程中的表面吸附

Surface Adsorption in the ALE GaAs Growth

本文以实验结果为基础,根据 ALE GaAs 生长过程中的自限特性和 Langmiur 单层吸附模型,计算了在 TMGa 暴露周期各化学物种的气相分压和表面复盖度随温度、TMGa 注入量和反应系统压力的变化关系。讨论了生长参数的改变对生长速率和 C 掺杂的影响。计算结果表明,温度对各物种在 GaAs 表面复盖度的影响十分显著,随着温度的上升,主要含 Ga 吸附物从(CH_3)_2Ca,CH_3Ga 转变为 GaH 和 Ga 原子。另外,在 GaAs 表面含 C 物种的复盖度随温度和反应系统压力的降低及TMGa 注入压力的上升而增加。ALE GaAs 生长较合适的反应温度和系统压力分别为700～800K 和几十～几百个托。

Based on the experimental results,according to the self-limitingcharacteristic in the ALE GaAs growth and Langmiur monolayer adsorptionmodel,temperature,TMGa dosage and reaction system pressure dependenceof the gas partial pressure and the surface coverage of various species inTMGa exposure period are calculated.The influence of growth parameters onthe growth rate and the carbon incorporation in the ALE GaAs are discussed.The resalts show that the coverages of various species on GaAs surface dependon the temperature evidently.The main Ga-containing species (CH_3)_2Ga,CH_3Ga change into GaH and atomic Ga as the temperature increases.In addition,the coverage of the C-containing adsorbates on GaAs surface increases withthe decreasing of the temperature and system pressure and the increasing ofTMGa injecting pressure.The suitable reaction temperature and system pressurefor ALE GaAs growth are 700—800K and tens to hundreds Torr,respectively.