Hot Wall Epitaxy Prepared CdSe/InAs/Si(211) Thin Film Material And Its Properties

As one of important II-VI materials,CdSe attracted widely attentions in the field of mid and long wavelength infrared detection devices,which has the room temperature band gaps of two kinds of CdSe crystals were 1.75 eV and 1.9 eV,respectively.Recommends cadmium selenide(CdSe)as a semiconductor well suited for optoelectrical application,such as photodetection or solar energy conversion.It has broad application prospect and important theoretical research value.In this paper,InAs films were optimized on Si(211)substrate with single side polishing by hot wall epitaxy(HWE),and the InAs films were optimized by heat treatment,in order to reduce the lattice and thermal expansion mismatch between Si and CdSe.Then,the CdSe film was prepared on the surface of InAs film.The structural,compositional,surface,optical and electrical analysis was completed with the help of XRD,SEM,AFM,UV-Vis spectrophotometer,FT-IR spectrometer and impedance analyzer,respectively.The effect of substrate temperature?evaporation temperature and proportion of Cd/Se on the phase structure,surface morphology,photoelectric property of CdSe films were studied.The experimental results obtained in this paper are as follows:1.InAs thin films were prepared on Si(211)substrate by hot wall epitaxy.The effects of different growth conditions and heat treatment on the structure and properties of InAs/Si(211)thin films were investigated.The InAs films were characterized by different analytical methods.The growth parameters of InAs/Si(211)films were obtained:the source temperaturethe is 950?,dehydrogenation temperature is 750 ?,arsenic activation of silicon surface temperature is 380 ?,the growth buffer layer temperature is 450 ?,the deposition time is 2 h.The experimental data include:the Hall mobility of InAs/Si(211)film arrived 3.12 x 102 cm2�V-1 �s-1,the resistivity was 1.56 ?�cm and the carrier concentration was 1.3 � 1016 cm-3.FTIR analysis shows that obtained InAs films in general with a blue shift,comparing with the band gap of InAs material.As a result,the growth conditions of InAs polycrystalline films with good crystal quality were determined.2.CdSe films were successfully prepared on surface of InAs films by HWE technique.The effects of different growth conditions on the deposition of CdSe thin films were investigated,including substrate temperature,evaporation source temperature and different source ratio.The best growth conditions for CdSe film is evaporation source temperature of 350 ?,the substrate temperature of 80 ?,Cd/Se = 1:9.XRD test results show that the CdSe film with zinc blende structure along with the(111)preferred orientation.SEM and AFM test results to obtain the film surface is uniform and smooth;FT-IR tests show that the CdSe stretching vibration absorption peak in the normal range;UV-vis test shows that the band gap of CdSe is 1.70?2.45 eV with a blue shift phenomenon.Hall tests were obtained for CdSe films with a Hall mobility of 2.0 � 102 cm2�V-1�s-1,a resistivity of 2.608 ?�cm and al.2 � 1016 cm-3.As a result,the growth conditions of CdSe/InAs/Si(211)polycrystalline films with good crystal quality were determined.