Characterization of Electronic Structures of Deep Levels in Semiconductors by Magneto-Circular Emission Spectrum

(1)半导体深能级电子结构的研究综述了有关半导体深能级电子结构的实验和理论研究，重点介绍了由过渡原子杂质引起的深杂质能级的电子结构。(2)磁圆二向色性光谱装置的设计、安装和调试。该装置由卤钨光源、单色仪、椭球面镜光学系统、偏振器、压电双折射调制器、极片穿孔电磁铁、氦低温恒温器、制冷机和红外探测用半导体光电池组成。该装置配备了电子系统，包括两个锁定放大器和一个基于微处理器的数据采集系统…更多的泰姆。(3)样品的制备用水平布里奇曼(HB)法制作了掺铬半绝缘砷化镓(HB)晶片，用液封提拉法(LEC)生长的非掺杂半绝缘砷化镓晶片、不同电导率类型(p、i、n)的掺铟无位错砷化镓晶片和掺铁的LEC生长的InP晶片被切割和抛光，作为MCD测量的样品。MCD光谱的测量和理论分析所有被测样品都显示出MCD结构在基态能隙以下的特征，这与晶体的性质有关。在这些光谱中，根据量子缺陷模型分析了与HB生长的GaAs：Cr的光电离跃迁相关的MCD谱，假定该跃迁发生在自旋-轨道-分裂价带到与铬相关的深态。计算得到的能级阈值为0.89 eV，自旋轨道参数为0.2 eV，与实验结果吻合较好。后者的值与价带分裂的已知值相比太小了，即0.35 eV。MCD作为一种晶体评价技术发现，MCD光谱对结晶度非常敏感；例如，热处理使光谱形状发生了很大的变化。因此，很明显，如果我们能够对不同处理的晶体进行MCD数据分类，该技术可以用作晶体性质的评估方法。较少

(1)Survery of electronic structures associated with the deep levels in semiconductorsExperimental and theoretical studies concerning the electronic structures of deep impurity levels in semiconductors were surveyed with particular reference to those introduced by transition atom impurities.(2)Layout, setup and abjusting of apparatus for magneto-circular dichroism spectrumBy combining optical elements purchased by this grant-in-aid, apparatus for the measurement of magneto-circular dichroism spectrum in the near-infrared region was constructed. This apparatus consists of a halogen-tungsten light source, a monochromator, an optical system with ellipsoidal mirrors, a polarizer, a piezo-birefringent modulator, an electromagnet with a perforation through its pole-pieces, a cryostat with helium a refrigerator and a semiconductor photocell for infrared detoction. This apparatus is equipped with an electronic system including two lockin-amplifiers and a microprocessorbased data-acquisition sys … More tem. This apparatus is capable of measuring the MCD for 0.4- 2.4um with magnetic field up to 13kG between temperatures from 20K to 300K.(3)Preparation of specimensChromium-doped semi-insulating GaAs wafers with different concentration of chromium made by the horizontai Bridgmann(HB)-method, an undoped semi-insulating GaAs wafer grown by liquid encapsulated Czochralski(LEC) technique, indium-doped dislocation-free GaAs ingots with different conductivity types(p,i,n) and LEC-grown InP wafers doped with iron were cut and polished to serve as specimens for the measurement of MCD. Heat treatment in arsemic atmosphere or chromium diffusion was also carried out.(4)Measurement and theoretical analysis of MCD spectraAll specimens measured showed MCD structures below the fundamental energy gap characteristic to the nature of the crystal. Among these spectra, MCD spectrum associated with the photoionization transition in HB-grown GaAs:Cr was analyzed in terms of the quantum defect model assuming the transition occurs from spin-orbit-split valence bands to Cr-related deep states. The calculated spectrum fit to the experimental one was satisfactory with the energy threshold 0.89eV and spin-orbit parameter of 0.2eV. The latter value is too small compared with that known for valence band splitting; i.e. 0.35eV. This suggests that a modification of the theory is necessary.(5)MCD as a crystal evaluation techniqueIt was found that MCD spectrum is very sensitive to crystallinity; for example the spectral shape changes drastically by heat treatment. Therefore, it becomes clear that the technique can be used as an evaluation method for crystal properties if we can classify MCD data for crystals with different treatments. Less