Эллипсометрический метод измерения температуры буферных слоев CdTe в технологии молекулярно-лучевой эпитаксии CdHgTe

An ellipsometric procedure developed for noncontact in situ measurement of the CdTe buffer-layer temperature is presented. The procedure is based on the temperature dependence of the energy position of CdTe critical points and is intended for determining the initial temperature of the growth surface before epitaxy of the cadmium–mercury–telluride compound. An express method for determining the position of critical points by the spectra of ellipsometric parameter Ψ is proposed. A series of calibrated experiments is performed. They result in determination of the temperature dependences of the position of critical points. Estimations and the experiment show that the temperature-measurement accuracy is ±3°C.

Nanostructure of Pure Iron Anodically Oxidized in Borate Buffer Solution and Annealed by Infrared Radiation

The behavior of oxide film on pure iron passivated in a borate buffer solution and subsequently radiated by infrared light (IR) was investigated in comparing to that by just IR annealing without passivation, and was evaluated by film structure, etc. The effect of thermal annealing over 250 °C was observed with γ-Fe2O3 grain growth and sharp increase in surface roughness, film thickness and oxygen content. An ellipsometric parameter of tanΨ was sensitively reflected by annealing effect, and tanΨ curve had a shoulder at 150 °C for 5 min and a peak of tanΨ was shifted from 350 nm to 450 nm in wavelength. This shift was also caused by the formation of γ-Fe2O3, because the peak was also observed in tanΨ of the bulk Fe2O3 family. Passivation effects at 800 mV prior to IR annealing on thickness and oxygen content changed at 150 °C, and decreased tanΨ at 350 nm and excessive film growth over 250 °C, and increased oxygen content under 100 °C and surface roughness at 50–250 °C. The terrace width with atomic scale flatness was slightly increase by passivation prior to IR annealing at 50–250 °C, and the maximum terrace width reached larger than 10 nm by passivation and IR annealing at 100 °C for 30 min.

The Growth Of High-Quality MCT Films by MBE Using in Situ Ellipsometry

The ellipsometry and RHEED study of MCT grown on (112) CdTe and GaAs by MBE was carried out. The dependence of ellipsometric parameter on composition is evaluated. As shown we can measure the growth rate, the roughness changing, initial temperature and composition by ellipsometry in situ. We investigated the evolution of roughness of film surface. We observed the appearance of surface roughness at initial stage of MCT growth under various composition (XcdTe0÷0.4). The following growth in optimal growth condition (including constancy of substrate temperature) gives us the smoothing of the surface and supplies us the high-quality MCT films. It is found that under constant temperature of substrate heater we can not grow the thick, perfect film of MCT. The concentration, mobility and life time of carriers in MCT films were respectively: n=1.8*1014 ÷8.2*1015cm−3, μn=44000÷370000cm2 V−1 s−1, τ=40÷220ns;p=1.8*1015÷8.4*1015 cm−3, μp=215÷284 cm2V−1 s−1 τ=12÷20ns.