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提出了利用Ga或GaAs-AsCl_3-H_2系统汽相生长GaAs的新方法。虽则生长装置与通用的Ga或GaAs-AsCl_3-H_2系统相同,但源和衬底之间的温度条件倒过来了。业已发现,在源温低于700℃以下时,氢气氛中的AsCl_3和源(GaAs或As饱合的Ga)之间的化学反应异常加速,AsCl_3对镓的输运系数(通常写成Ga/Cl)大大高于热力学所估计的值,提出了在源区内发生异常反应的必要条件:(1)源温必须低于700℃。(2)通入气体(H_2+AsCl_3)的流速必须相当高。利用这种异常的反应,无论在GaAs-AsCl_3-H_2还是在Ga-AsCl_3-H_2系统中都进行过外延生长,主要利用电微量天平检查了生长速率与源和衬底温度,氢流速以及AsCl_3克分子分数之间的关系,虽然异常反应的机构仍不知道,但提出了解释所观察到现象的简单模型。
A new method of vapor phase growth of GaAs using Ga or GaAs-AsCl 3 -H 2 system is proposed. Although the growth device is the same as the common Ga or GaAs-AsCl 3-H 2 system, the temperature conditions between the source and the substrate are reversed. It has been found that when the source temperature is below 700 ° C, the chemical reaction between AsCl_3 in the hydrogen atmosphere and the source (Ga or As-Ga) is abnormally accelerated, and the transport coefficient of AsCl_3 to gallium (usually written as Ga / Cl ) Is much higher than the values estimated by thermodynamics, and presents the necessary conditions for anomalous reactions in the source region: (1) The source temperature must be lower than 700 ° C. (2) The flow rate of the incoming gas (H 2 + AsCl 3) must be quite high. Using this anomalous reaction, the epitaxial growth has been carried out both in GaAs-AsCl 3 -H 2 and Ga-AsCl 3 -H 2 systems. The growth rate, source and substrate temperature, hydrogen flow rate and AsCl 3 The relationship between molecular fractions, although still unknown to an anomalous body, suggests a simple model to explain the observed phenomena.