A Novel Contactless and Nondestructive Measurement Method of Surface State Density on Semiconductor Free Surface, and Control of Their Surfaces

(1)提出了一种基于光致发光（PL）的半导体表面态密度（N_<ss>）测量方法（PL表面态光谱：PLS^3）。它包括详细测量带边光致发光效率随激发强度的函数，并通过计算机对其进行严格的分析。通过该方法，可以以无接触、无损的方式确定N_<ss>分布和表面复合速度S的值。(2)首次成功地将PLS^3技术应用于原位测定GaAs、InP、InGaAs和Si等不同加工自由表面的N_<ss>分布。化学蚀刻、阳极氧化和钝化表面以及原始接收表面产生u形表面态密度分布，其特征电荷中性能级为E_<HO>，符合无序诱导间隙态（DIGS）模型。本文还证实了该方法在评价MBE生长和光cvd等超高真空工艺方面的有效性。(3)结合开发的C-V模拟技术和PLS^3技术，揭示了MBE GaAs生长中断界面、晶格匹配界面和伪晶异质界面存在连续u形态。先前在界面周围观察到的载流子分布异常可以用这些连续状态来解释。(4)通过在Al/GaAs（100）中插入合适掺杂的超薄MBE Si界面控制层（Si ICL），可以在约400 meV的宽范围内精确控制Al/GaAs（100）的肖特基势垒高度。结果与肖特基势垒形成的模型一致。此外，在PCVD-SiO_2沉积前对GaAs表面进行HF处理可以有效抑制快速热退火过程中的界面反应。

(1) A novel photoluminescence (PL)-based measurement method (PL Surface State Spectroscopy : PLS^3) for semiconductor surface state density, N_<ss>, was newly developed. It consists of detailed measurement of the band-edge photoluminescence efficiency as a function of the excitation intensity, and its rigorous analysis by computer. By this method, N_<ss> distribution as well as the value of surface recombination velocity, S, can be determined in a contactless and nondestructive fashion. (2) The proposed PLS^3 technique was successfully applied for the first time for in-situ determination of the N_<ss> distribution on variously processed free surface of GaAs, InP, InGaAs and Si. Chemically etched, anodized and passivated surfaces, as well as the original as-received surface, give rise to U-shaped surface state density distributions with characteristic charge neutrality energy levels, E_<HO>, which is consistent with the disorder induced gap state (DIGS) model. The usefulness of the present method for the assessment of ultrahigh-vacuum-based processes, such as MBE growth and photo-CVD, was also confirmed. (3) Combined use of a developed C-V simulation technique and PLS^3 technique revealed the existence of continuous U-shaped states at growth interrupted interfaces of MBE GaAs, and lattice matched and pseudmorphic heterointerfaces. The previously observed carrier profile anomaly around the interface can be explained by these continuous states. (4) Schottky barrier height of Al/GaAs(100) can be precisely controlled over a wide range of about 400 meV by the insertion of an ultrathin MBE Si interface control layer (Si ICL) with suitable doping. The result is consistent with a proposed model for Schottky barrier formation. Moreover, HF treatment of GaAs surface before PCVD-SiO_2 deposition is highly effective in suppressing the interface reactions during rapid thermal annealing.