Crystal Growth of Thallium Containing III-V Semimetal-Semiconductor Alloys and Search of New Physical Properties

用气体源分子束外延法在InP衬底上生长了四元半导体TlInGaAs、TlInGaP，X射线衍射和电子探针测试证实了TlInGaAs和TlInGaP的成功生长。发现TlInGaAs的Tl组分随生长过程中Tl流量的增加而增加。光致发光（PL）结果表明，掺铊的TlInGaAs样品的带隙随温度的变化比GaAs，InP和InAs的带隙随温度的变化慢，掺铊6%的TlInGaAs样品的带隙随温度的变化比GaAs，InP和InAs的带隙随温度的变化慢。我们还生长了InP/TlInGaAs/InP的双异质结结构，X射线衍射和电子探针分析表明，这种双异质结结构的界面上没有发生III族原子的相互扩散，而且，我们观察到DH结构的形成使TlInGaAs层的光致发光强度增强，通过测量光电导谱的温度依赖性，我们还观察到TlInGaP的带隙能量的温度变化变慢。首次观察到了TIP的拉曼信号，其拉曼峰位于InP的低波数处，表明TlInGaAs在温度无关的波长激光二极管中有应用前景。

Quaternary semiconductors TlInGaAs, TlInGaP were grown on InP substrates by gas source MBE using elemental Tl, In and Ga, and thermally cracked arsine and phosphine.Substrate temperature during growth was 450ﾟC.X-ray diffraction and EPMA measurements confirmed the successful growth of TlInGaAs and TlInGaP.It was found that Tl composition of TlInGaAs increases with Tl flux during growth.Photoluminescence (PL) emission was observed from the grown TlInGaAs.PL peak wavelength was observed to increase with Tl composition and it was found that the bandgap is decreased by incorporation of Tl.Temperature dependence of PL spectra showed that the temperature variation of bandgap energy is slower than those of GaAs, InP and InAs.For the TlInGaAs with Tl composition of 6%, nearly temperature-independent bandgap energy was observed.This result agrees well with our expected properties.We also have grown the double-hetero (DH) structure of InP/TlInGaAs/InP.From the X-ray diffraction and EPMA measurements on this DH structure showed that the interdiffusion of group III atoms at the interfaces was not occurred.Furthermore, we have observed the enhancement of PL intensities from TlInGaAs layer by the formation of DH structures.Slower temperature variation of bandgap energy was also observed for TlInGaP by the measurement of temperature dependence of photoconductance spectra.We have observed the TIP Raman signals for the first time.The Raman peaks were located at lower wavenumbers of those of InP.It was suggested that TlInGaAs is promising for the application to the temperature-independent wavelength laser diodes.