讨论了半导体pn结内建电场和接触电势的形成与可测性，回答了在半导体物理学pn结内容教学中学生经常会提出的一个似是而非的问题。从热力学第一定律、金属-半导体接触等不同角度详细解释了热平衡（零偏下）时pn结不可能对外输出电压和电流的原因。

This paper reports the annealing process influence on interfacial electrical properties, dopant effects on silicide formation, and dopant redistribution during silicidation in self-aligned NiSi technology. The reverse leakage current results of NiSi/n-Si Schottky diodes show that two-step rapid thermal process (RTP) significantly improves the NiSi/Si area-contact characteristics in comparison with one-step RTP, and low temperature in RTP1 is beneficial to the final Ni-silicide/Si contact properties. Both structural and electrical characterization shows substantially different Ni-silicidation behaviors on heavily-doped n+ and p+ Si substrates at low temperature (300℃). The larger grain size of Ni2Si formed on heavily As-doped Si is responsible for the lower resistivity, comparing with Ni2Si formed on heavily B-doped Si. Ni/Si reaction on highly doped Si substrates also results in significant dopant segregation at the silicide/Si interface and pile up in void-layer formed just underneath the silicide surface.

Schottky and pn junction diodes with good rectifying characteristics have been prepared based on the polycrystalline SiGe (poly-SiGe) thin film deposited by the ion-beam-sputtering (IBS) technique. Boron and phosphorus diffusion techniques have been used to dope and crystallize as-deposited amorphous SiGe film. Rectification ratios as high as 4000 and 1800 have been achieved in Pt/n-poly-SiGe and Ti/p-poly-SiGe Schottky diodes, respectively, while rectification ratio higher than 1500 and breakdown voltage higher than 200V have been achieved in poly-SiGe pn junction diodes. Schottky barrier height has been determined to be 0.62 and 0.59 eV for Pt/n-poly-Si0.81Ge0.19 and Ti/p-poly-Si0.81Ge0.19 contacts, respectively, which indicates that the band alignment of poly-SiGe may be substantially different from that of epitaxial SiGe.

Conventional dopant diffusion technique has been successfully employed to dope SiGe films deposited by ion-beam sputtering (IBS). The deposited a-SiGe films can be doped to both p and n types after boron and phosphorous diffusions at a temperature range of 850-1000℃. The doping process is accompanied by crystallization of the a-SiGe film. Electrical properties of the doped SiGe films have been characterized by a four-point probe and Hall measurements. Hall mobilities as high as 13 and 31cm2/V·s have been obtained in boron-and phosphorous-doped polycrystalline SiGe films, respectively.

Amorphous Si0.87Ge0.13 is deposited on n-Si (100) substrate by ion beam sputtering (IBS) and doped through thermal diffusion of phosphorus to fabricate n-poly-Si0.87Ge0.13 thin film. The formation of Schottky junction is made by deposition Ni on n-poly-Si0.87Ge0.13 by IBS. Solid-phase reaction mainly occurred above 400℃ by rapid thermal annealing at the interface of Ni/n-poly-Si0.87Ge0.13. Phase identification and depth profile were investigated by X-ray diffraction (XRD) and Auger electron spectroscopy (AES), respectively. The electrical properties of both unannealed and annealed Ni/n-poly-Si0.87Ge0.13 were studied by current-voltage (I-V) measurement. The results demonstrate that the Schottky barrier height (SBH) changes little with the annealing temperature between 300 and 600℃. The constancy of SBH is attributed to the properties of the interface itself which determine the SBH and substantially independent of whether the interfacial material is nickel or nickel germanosilicide.