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。

Thermal stability, phase and interface uniformity of Ni-silicide are some key issues for NiSi Salicide technology. The improved stability of NiSi was achieved by Ni/Pt/Si and Ni/Pd/Si reaction. The increase of thermal stability can be explained by classical nucleation theory. The phase and interface uniformity of Ni-silicides formed by Ni-Si solid-state reaction were characterized by X-ray diffraction (XRD) and temperature-dependent current-voltage (I-V-T) techniques. Results show that the Schottky barrier height (SBH) inhomogeneity characteristic has strong dependence on annealing temperature for Ni-silicide formation. Deep level transient spectroscopy (DLTS) measurement shows that annealing at relatively low temperature may cause electrically active deep level defects in the film. These results show that choosing a proper annealing temperature for Ni/Si silicidation will be very important for device performance.

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.

The electrical and materials properties of～20nm nickel silicide films, formed at 300℃, on n+/p and p+/n junctions are investigated. The sheet resistance of the silicide on p+/n junctions is found to be more than twice as high as that of the silicide on n+/p junctions. Cross section transmission electron microscopy, Rutherford backscattering spectroscopy, and x-ray photoelectron energy spectroscopy reveal that a pure Ni2Si layer forms on n+/p junctions while a thicker Ni2Si/NiSi double layer (～60% Ni2Si) forms on p+/n junctions. But the electrical differences are found to correlate only with differences in grain size and dopant concentration in the silicide.

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.