Growth and Properties of (III-V)-(II-VI) Super Lattices by Photo-Assisted Atomic Layer Epitaxy

由III-V复合阱（GaAs）和II-VI复合势垒（ZnSe）组成的一种新型应变层超晶格（SLSs）有望成为工作在可见光区的新型光电器件的材料。制造SLSs的困难之一是GaAs和ZnSe外延温度的差异。此外，虽然在250 - 350℃的低温下，在GaAs上生长ZnSe是相当容易的，但在这样的温度下，在ZnSe上生长GaAs是相当困难的，因为as在ZnSe上的粘附系数很小。因此，降低外延温度对于制备GaAs- znse SLSs是非常重要的。这也有效地抑制了GaAs和ZnSe之间的交叉扩散，并在它们之间获得了原子控制的锐界面。(1)利用MOVPE和MOMBE实现了ZnSe和ZnS在GaAs上的原子层外延。(2)用氩离子激光线照射GaAs表面，可以显著降低ZnSe在GaAs表面的外延温度，这是由于ZnSe表面发生了光催化反应。(3)还发现光照射对降低GaAs在ZnSe上的外延温度非常有效，这也归因于ZnSe上的光催化作用。(4)利用表面光吸收（SPA）和反射差谱（RDS）技术，建立了GaAs和ZnSe层外延的原位监测技术。(5)对GaAs-ZnSe SLS的光学性质进行了理论计算，并对SLS结构进行了优化。在这些结果的基础上，GaAs-ZnSe SLSs的制备和表征正在进行研究。

A new type of strained layer superlattices (SLSs) consisting of III-V compound wells(GaAs)and II-VI compound barriers(ZnSe)are expected as materials for new optoelectronic devices operating in visible region. One of the difficulties when fabricating the SLSs is the difference in epitaxy temperatures for GaAs and ZnSe. Further, although it is fairly easy to grow ZnSe on GaAs at such low temperatures as 250 - 350 C, it is quite difficult to grow GaAs on ZnSe at such temperatures, because the sticking coefficient of As on ZnSe is quite small. Therefore, lowering the epitaxy temperature, especially for GaAs, is very important to fabricate the GaAs-ZnSe SLSs. This is also effective to suppress the cross diffusion between GaAs and ZnSe and also to obtain atomically controlled sharp interfaces between them.(1) Atomic layer epitaxy of ZnSe and ZnS on GaAs has been achieved by MOVPE and MOMBE.(2) It has been shown that the epitaxy temperature for ZnSe on GaAs can be drastically lowered by irradiating the growing surface with Ar ion laser lines, and this has been attributed to the photocatalytic reaction on the ZnSe surface.(3) It has also been found that photoirradiation is very effective to lower the epitaxy temperature for GaAs on ZnSe, which is also attributed to the photocatalysis on ZnSe.(4) In-situ monitoring technique has been developed for epitaxy of GaAs and ZnSe layers utilizing surface photoabsorption (SPA) and reflectance-difference spectroscopy (RDS).(5) Optical properties of GaAs-ZnSe SLSs have been theoretically calculated and optimization for the SLS structures has been done.On the basis of these results, fabrication and characterization of GaAs-ZnSe SLSs are under investigation now.