Growth of InAsSb alloy layrs by compositional conversition and its application to mid-infrared sensing devices

InAsSb合金是一种很有前途的中红外器件材料。然而，由于缺乏与合金相匹配的衬底晶格，使得高性能器件的制作变得困难。为了克服这一问题，采用“成分转换”方法在目前可用的复合晶体衬底上形成了具有所需成分的InAsSb合金层。首先，研究了在高熔点衬底(InAs)上生长低熔点晶体(InSb)的过程，结果表明，在较高的生长温度下，可以实现层状生长。对于在InAs衬底上生长InSb的情况，温度范围在390℃到440℃之间较好，所制备的样品被接触到饱和了合金组分的三元溶液中，称为转化过程。实验表明：高Tf合金成分在低Tf生长层中的扩散很大，因此低Tf生长层在成分中立即转化；在随后的一段时间内，成分的均质化和晶格修复的推进；最终的合金成分在所用的溶液中达到平衡成分；因此，通过调整溶液的成分可以实现所需成分的合金层；在此转化过程中，具有最高Tf的基片是稳定的。在转化后的合金层上连续生长的合金表明，生长的合金的结晶质量有了很大的提高，从而开拓了InAsSb合金在器件中的应用前景。基于所获得的知识，可以制造中红外设备，从而在不久的将来改进所需的信息通信系统和/或空气污染监测系统。

InAsSb alloy is a promising material for mid-infrared devices. However the lack of a substrate lattice-matched to the alloy system makes it difficult to fabricate the higt performance devices. To overcome this problem, "compositional conversion" was applied to the formation of InAsSb alloy layrs with desired composition on a compound crystalline substrate available at present. In this technique, melting point (Tf) of the materials plays an important role to grow the alloy layr.At first, the growth of low Tf crystal (InSb) on a higt Tf substrate (InAs) was investigated and made it clear that layr-mode growth is obtained at relatively higt growth temperature. In the case of InSb growth on InAs substrates, the temperature range between 390C and 440C is preferable.The samples prepared were contacted to ternary solution saturated with alloy components, named "conversion process". The experiments made clear the following points : the diffusion of a high Tf alloy components into the low Tf grown layr is very high ; therefore the low Tf grown layr converts immediately in its composition ; homogenization in composition and lattice repairing advances in the following period ; the final alloy composition reaches to an equilibrium composition with the solution used ; therefore the alloy layrs with desired composition can be realized by adjusting the composition of the solution ; the substrate with the highest Tf is stable during this conversion process. Successive growth of alloy on the converted alloy layrs showed that the crystalline quality of grown alloy is drastically improved.Thus, the prospects for device application of InAsSb alloy was developed. Based on the knowledge obtained, the mid-infrared devices could be fabricated, making progress an information-communication system and/or an air pollution watching system demanded in near future.