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

(1)提出了一种新的基于光致发光的半导体表面态密度测量方法(PL表面态光谱)。它包括详细测量带边光致发光效率随激发强度的变化，并用计算机进行严格的分析。用这种方法可以非接触、无损地确定N_1分布和表面复合速度S的值。(2)首次将所提出的偏最小二乘法成功地应用于不同加工工艺的GaAs、InP、InGaAs和Si的自由表面上N_&lt；ss&gt；分布的原位测量。经过化学腐蚀、阳极氧化和钝化的表面以及原始接收表面，产生了具有特征电荷中性能级E&lt；Ho&gt；的U型表面态密度分布，这与无序诱导能隙(DIGS)模型一致。本方法对分子束外延生长和光化学气相沉积等基于超高真空工艺的评估也是有效的。(3)用改进的C-V模拟技术和偏最小二乘法相结合的方法，揭示了分子束外延生长中断界面、晶格匹配异质界面和赝形异质界面存在连续的U形态。以前观察到的界面附近的载流子分布反常可以用这些连续态来解释。(4)通过引入适当掺杂的超薄分子束外延硅界面层(SiICL)，Al/GaAs100的肖特基势垒高度可以在400 meV左右的较宽范围内精确控制。计算结果与肖特基势垒形成模型一致。此外，在PCVD-SiO_2沉积前对GaAs表面进行高频处理，可以有效地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.