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在3～5和8～12μm 波段,碲镉汞(MCT)已成为红外探测和热成象的最重要的半导体材料。目前,高质量光电二极管可利用包含离子注入形成 n-p 结的工艺来制作。但是,掺杂机理还说不清楚,因为这种化合物半导体的电学性质,不仅由杂质决定,而且还由“缺陷”及与化学配比的偏离所决定。离子注入 MCT 的主要特征是:在注入的材料中,退火前观察到的是 n~+电学掺杂。“缺陷”似乎是产生这个现象的原因,因为形成这一 n~+层不需要任何进一步退火,同时也不怎么依赖注入条件及注入离子的性质。本文描述了离子注入 MCT 的一般性质。我们将给出观测缺陷所引起的载流子浓度饱和、结迁移和退火材料性质等许多问题。这些问题的回答有助于了解离子注入 MCT 的掺杂机理。看来经过注入杂质,接着进行退火的掺杂也是一个更为复杂的问题,因为它主要与缺陷的退火和化学配比的控制有关。p 型掺杂杂质和 n 型掺杂缺陷之间的竞争,提出了通过离子注入形成 p 型层的可能性问题。
In the bands 3-5 and 8-12 μm, mercury cadmium telluride (MCT) has become the most important semiconductor material for infrared detection and thermal imaging. Currently, high quality photodiodes can be fabricated using a process that includes ion implantation to form n-p junctions. However, the doping mechanism is still unclear as the electrical properties of such compound semiconductors are determined not only by impurities but also by “defects” and deviations from the stoichiometry. The main feature of ion implantation of MCT is that in the implanted material, n ~ + electrical doping is observed before annealing. “Defects” appear to be responsible for this phenomenon because the formation of this n + layer does not require any further annealing and does not depend so much on the implant conditions and the nature of the implanted ions. This article describes the general nature of ion implantation MCT. We will show many problems such as saturation of the carrier concentration, junction migration and properties of the annealed material caused by the observed defects. The answers to these questions help to understand the doping mechanism of ion implantation in MCT. It seems that after the implantation of impurities, the subsequent doping of the anneal is also a more complex issue as it is mainly due to the control of the annealing and chemical stoichiometry of the defects. The competition between p-type dopant impurities and n-type doping defects has raised the question of the possibility of forming a p-type layer by ion implantation.