EXCIMER LASER DOPING FOR WIDE-GAP SEMICONDUCTORS

宽禁带II-VI半导体的p型掺杂是器件制造中与金属电极形成欧姆接触的关键技术。采用含有掺杂原子的碱金属化合物K2S、Na2Se或Na2Te，对ZnSe和CdTe进行了准分子激光掺杂实验。电学性能对该处理的影响主要通过霍尔测量来测量。ZnSe的电阻率从105急剧下降到10-2 ohm cm，空穴载流子浓度增加到4.8 × 1019 cm-3。采用含掺杂原子的Na2Te作为化合物，采用激光掺杂方法，CdTe的电阻率也从105降低到10-1欧姆cm。研究了CdTe p-i-n二极管中p型欧姆接触的形成。我们将该技术进一步扩展到空间模式掺杂。用条形探测器的图样证明了空间图样的掺杂。这些掺杂技术为集成碲化镉二维成像系统的制造提供了良好的前景。碲化镉具有吸收系数高、带隙大、空穴迁移寿命积好以及在正常大气条件下的稳定性等优点，是一种有吸引力的用于固态高能x射线和伽马射线成像系统的半导体材料。这种技术对于集成伽马射线探测器的制造是必不可少的。

p-type doping of wide band gap II-VI semiconductors is a key technology to form the ohmic contact with metal electrodes in device fabrications. Using an alkaline metal compound such as K2S, Na2Se or Na2Te which contains dopant atoms, excimer laser doping experiment were carried out for ZnSe and CdTe. Influence of the electrical properties on this treatment was mainly measured by mean of the Hall measurement. The resistivity of ZnSe drastically decreased from 105 to 10-2 ohm cm and the value of holwe carrier concentration increased up to 4.8 x 1019 cm-3.For CdTe, also resistivity decreased from 105 to 10-1 ohm cm by laser doping method using Na2Te as a compound including dopant atoms. Formation of p-type ohmic contact in CdTe p-i-n diode was also investigated. We have further extended this technique for doping with spatial pattern. The spatially patterned doping is demonstrated with strip detector patterns. These doping techniques are promising for the fabrication of integrated CdTe two-demensional imaging system.CdTe is an attractive semiconductor material for applications in solid-state high energy X-ray and gamma ray imaging systems because of its high absorption coefficient, large bandgap, good mobility life time product of holes and stability at normal atmospheric conditions. This technique will be essential for integrated gamma ray detector fabrications.