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将掺磷的Hg_(0.8)Cd_(0.2)Te单晶样品放在不同汞分压中,使其在450℃到600℃温度范围内退火。待样品冷却到室温后测量霍耳效应和迁移率,发现所有样品均为p型,其空穴浓度远小于晶体中磷的总浓度。空穴浓度也随着汞分压的增加而增加,这和在不掺杂晶体中观察出的现象不大相同。同时,在低汞压下,掺杂样品中,空穴浓度比不掺杂晶体中空穴浓度小。在77K时掺杂样品中的空穴迁移率接近于非掺杂样品中的空穴迁移率。这些结果表明磷在Hg_(0.8)Cd_(0.2)Te(s)中呈现两重性,在高汞压下磷占据了填隙和碲的晶格点位置而呈现为一价的受主,在中低汞压下磷占据汞的晶格点而表现为一价的施主,由于填隙和代位的磷结合形成配对,因而大多数的磷似乎是以电中性对的形式存在。在低汞压情况下大部分磷似乎是以代位磷和汞空位形成的带正的和负的电荷对出现。本文计算了各类磷结合方式的热力学常数,满意地解释了这些实验结果。
The Hg_ (0.8) Cd_ (0.2) Te single crystal doped with phosphorus was placed in different mercury partial pressure and annealed in the temperature range from 450 ℃ to 600 ℃. After the sample was cooled to room temperature, the Hall effect and the mobility were measured. All the samples were found to be p-type and the hole concentration was much smaller than the total concentration of phosphorus in the crystal. Hole concentration also increases with increasing mercury partial pressure, which is not the same as observed in undoped crystals. At the same time, the hole concentration in the doped sample is lower than that in the undoped crystal under low mercury pressure. The hole mobility in the doped sample at 77K is close to the hole mobility in the undoped sample. These results indicate that phosphorus presents duality in Hg_ (0.8) Cd_ (0.2) Te (s). Under high mercury pressure, phosphorus occupies the lattice sites of interstitials and tellurium and assumes monovalent acceptor. Mercury underlying phosphorus occupies the lattice point of mercury and appears as a monovalent donor. As a result of interstitial and substitutional phosphorus binding to form pairs, most of the phosphorus appears to exist in the form of electrically neutralized pairs. Most of the phosphorus at low mercury pressures appears to be positive and negative pairs of charges based on substitutional phosphorus and mercury vacancies. In this paper, the thermodynamic constants of various types of phosphorus binding are calculated and these experimental results are satisfactorily explained.