| Metal-semiconductor contacts are very important in technology. They are widely used in semiconductor devices and integrate circuits. The quality and reliability of semiconductor devices and integrate circuits greatly rely on the properties of metal-semiconductor contacts. The valence band offset AE, and conduction band offset Aî–© of heterojunction interface determine the depth of potential well and other basic properties of quantum well and superlattice. It is an important ingredient of modern "energy band project" to predict, modify or control the band offset (namely energy band clipping). The experimental and theoretical study of Schottky barrier of metal-semiconductor contact and band offset of heterojunction is closely related to the progress of new subject on surface and interface. Based on different experimental results, different theoretical models on Schottky barrier and heterojunction band offset have been proposed using different reference levels. In this thesis, we studied the intrinsic relationship between average-bond-energy Em and Fermi-level Eh- in energy bands of free electrons and metals. We find that the average-bond-energy is equivalent to Fermi-level. For semiconductor, average-bond-energy and "innate Fermi-level" have same physical connotation. A theoretical calculation method was established that can be applied to both Schottky barrier and heterojunction band offset, i.e. average-bond-energy method. Combined with the deformation potential, the average-bond-energy method was extended to the study of strained layer heterojunction band offset. Based on the character of average-bond-energymethod, we brought forward a simplified model to calculate strained layer heterojunction band offset. This dissertation is composed of five chapters. Chapter 1 is concerned with the research background and theoretical basis. The main contents and results of Chapters 2 - 5 are summarized as follows.In Chapter 2, we investigated the relationship of average-bond-energy and Fermi-level EF (free) in free electronic energy band by studying ten face-centered cubic semiconductor crystals, Si, Ge, GaP, InP, AlAs, GaAs, InAs, AlSb, GaSb and InSb, three hexagonal metal crystals,Ti, Zr, Hf, and body-centred tetragonal metal crystal, P - Sn. The valence electrons were approximated by free electrons. The Fermi-level EF(free) was calculated according to the radius of Fermi sphere filled by free electrons. The free electronic energy bands, under the equilibrium state and the strain states of hydrostatic pressure and the uniaxial strain, respectively, were considered. The Fermi-level EFID(free) was computed based on the highest filled state of electrons in the free electronic energy band. According to the calculated eigenvalues of free electronic energy band, the average-bond-energy Em was obtained using the equation (1.2.11) in this dissertation. The results indicate that not only the average-bond-energy Em and the Fermi-level EF(free) (or E,,'D(free)) are very close to each other under the equilibrium states, but also they obey the same variation rule under the strained states. Therefore, Em is equivalent to Eh-(free) in free electron energy band model. Equation (1.2.11) can be used to calculate the Fermi-level EF(free) of free electron system.In Chapter 3, we studied the relationship of average-bond-energy Em and Fermi-level Ef in metal energy band. The energy band of the metal crystals with hexagonal close-packed structure, Ti, Zr, Hf, and body-centred tetragonal P - Sn were calculated by the first principle pseudopotential method. The Fermi-level E'?was determined by the highest filled state of valence electrons. It is found that the average-bond-energy Em of these four metals is also very close to the Fermi-level Ef . The variation trends of Em and Ef with the number Np ofplane wave base function adopted in the energy band calculation are similar. The regularity of EHI and E'f changing with the strained states of hydrostatic pressure and uniaxial strain are the same. Therefore, as in the case of free...
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