Characterization and Control of Interaction between Quantized Energy Levels and Surface/Interface States in Compound Semiconductor Quantum Structures.

本研究的目的是研究化合物半导体量子结构中量子化能级与表面/界面态之间的相互作用，并研究新型硅层间钝化技术在化合物半导体量子结构钝化中的适用性。主要结果概述如下。(1)结果表明，当AlGaAs/GaAs量子威尔斯阱（QW）的厚度小于10 nm时，近表面QW的光致发光强度随势垒层厚度的减小而呈指数衰减，这种衰减是由于量子阱能级与表面态之间的相互作用所致。(2)本文提出了一种新型的化合物半导体表面钝化技术，即利用单晶硅/Si_3N_4双层膜作为界面控制层。(3)通过应用这种新的钝化技术，使InGaAs MIS系统的界面态密度急剧降低到2 × 10 ~（-3）<10>cm ~（-3<-2>）。该值是迄今为止化合物半导体MIS系统报告的最低值。(4)将该钝化工艺应用于Al_<0.3>Ga_<0.7>As/GaAs/Al_<0.3>Ga_<0.7>As近表面Qs的钝化。PL强度的完全恢复实现了所观察到的最大恢复因子为1000。PL强度的恢复可以解释为通过新颖的钝化过程减少界面态密度，导致通过隧穿过程减少非辐射表面复合。本发明的钝化技术可应用于化合物半导体量子结构的表面/界面控制。

The purpose of the research is to investigate an interaction between the quantized energy levels and the surface/interface states in compound semiconductor quantum structures, and to investigate the applicability of the novel silicon-intelayr based passivation technique to passivation of compound semiconductor quantum structures. The main results are summarized below.(1) It has been shown that the photoluminescence (PL) intensity from the near-surface AlGaAs/GaAs quantum wells (QWs) decreases exponentially with decreasing the thickness of the top AlGaAs barrier layr below 10nm, and that this PL reduction is due to the interaction between the quantized QW enegy levels and the surface states.(2) The novel passivation technique for compound semiconductor surfaces was successfully developed, in which an ultrathin silicon/Si_3N_4 double-layr is utilized as a interface control layr (ICL).(3) A drastic reduction of interface state density into the 2*10^<10>cm^<-2> was obtained for the InGaAs MIS system by application of the novel passivation technique. This value is the lowest reported so far for the compound semiconductor MIS systems.(4) The novel passivation process was applied to passivation of Al_<0.3>Ga_<0.7>As/GaAs/Al_<0.3>Ga_<0.7> As near-surface Qs. Complete recovery of the PL intensity was achieved with an observed maximum recovery factor of 1000. The recovery of PL intensity can be explained by reduction of interface state densities by the novel passivation process, resulting in reduction of non-radiative surface recombination via tunneling processes. The present passivation technique can be applicable to surface/inteface control of compound semiconductor quantum structures.