生长温度对In_(0.53)Ga_(0.47)As/InP的LPMOCVD生长影响

Effect of Growth Temperature on Properties of In_(0.53) Ga_(0.47) As/InP Grown by LPMOCVD

利用LPMOCVD技术在InP衬底生长了InxGa1-xAs材料 ,获得表面平整、光亮的In0 53 Ga0 47As外延层。研究了生长温度对InxGa1-xAs外延层组分、表面形貌、结晶质量、电学性质的影响。随着生长温度的升高 ,为了保证铟在固相中组分不变 ,必须增加三甲基铟在气相中的比例。在生长温度较高时 ,外延层表面粗糙。生长温度在 6 30℃与 6 5 0℃之间 ,X射线双晶衍射曲线半高宽最窄 ,高于或低于这个温度区间 ,半高宽变宽。迁移率随着生长温度的升高而增加 ,在 6 30℃为最大值 ,然后随着生长温度的升高反而降低。生长温度降低使载流子浓度增大 ,在生长温度大于 6

Indium gallium arsenic are now of considerable commercial importance in optoelectronics. For example HBT, HEMTs, FET and Detectors. Very high quality is required to fabricate these devices, in terms of electrical and optical properties. The epilayer properties are known to be very sensitive to growth parameters (growth temperature,Ⅴ/Ⅲ ratio, etc.). It is important to find suitable growth temperature for good quality epilayer properties. The effects of growth temperature on solid composition, surface morphology, crystal quality and electrical properties were investigated for InGaAs. In 0 53 Ga 0 47 As was grown by low pressure metalorganic chemical vapor deposition on semi insulating Fe doped InP substrate. The substrates were misoriented 2～5° toward (110). Precursors were trimethylindium(TMIn) and trimethylgallium(TMGa) for group Ⅲ, arsine(AsH 3) and phosphine(PH 3) for group Ⅴ. The growth temperatures ranged from 500～680℃. Before the epitaxy of InGaAs, an InP buffer layer was grown with 0.1μm. The composition of InGaAs was determined by X ray diffraction. The surface morphology was examined with SEM. Electrical properties were investigated by Hall effect measurements at room temperature. The mirror like and featureless morphology of In 0 53 Ga 0 47 As epilayer was attained. In order to keep indium solid composition constant, TMIn vapor composition increase with growth temperature increasing. The pyrolysis temperature of TMGa is higher than that of TMIn which pyrolyzed completely at 500℃. In the range of 500～650℃, the TMGa pyrolysis efficiency increase rapidly with increasing growth temperature. In the range of 650～680℃, because of a larger volatilization rate of indium from surface which is greater than that of gallium , the surface morphology became rough above 680℃. The FWHM of X ray rocking curve is a good indication of the epilayer quality. A plot the X ray rocking curve FWHM as a function of growth temperature show a low values between 630℃ and 650℃ but it rises at both higher and lower temperatures. The mobility increase with growth temperature increasing under 630℃. The mobility decrease with growth temperature increasing above 630℃.The best mobility can be obtained at 630℃. At low growth temperature the carrier concentration increase dramatically. This is attributed to enhance carbon incorporation.