A review of the properties of hydrogen in crystalline semiconductors is presented. The equilibrium lattice positions of the various states of hydrogen are detailed, together with the reactions of atomic hydrogen with shallow and deep level impurities that passivate their electrical activity. Evidence for several charge states of mobile hydrogen provides a consistent picture for both the temperature dependence of its diffusivity and the chemical reactions with shallow level dopants. The electrical and optical characteristics of hydrogen-related defects in both elemental and compound semiconductors are discussed, along with the surface damage caused by hydrogen bombardment. The bonding configurations of hydrogen on semiconductor surfaces and the prevalence of its incorporation during many benign processing steps are reviewed. We conclude by identifying the most important areas for future effort.

Hydrogen in crystalline semiconductors

p-Type ZnO materials: Theory, growth, properties and devices

Abstract In the past 10 years, ZnO as a semiconductor has attracted considerable attention due to its unique properties, such as high electron mobility, wide and direct band gap and large exciton binding energy. ZnO has been considered a promising material for optoelectronic device applications, and the fabrications of high quality p-type ZnO and p–n junction are the key steps to realize these applications. However, the reliable p-type doping of the material remains a major challenge because of the self-compensation from native donor defects (V O and Zn i ) and/or hydrogen incorporation. Considerable efforts have been made to obtain p-type ZnO by doping different elements with various techniques. Remarkable progresses have been achieved, both theoretically and experimentally. In this paper, we discuss p-type ZnO materials: theory, growth, properties and devices, comprehensively. We first discuss the native defects in ZnO. Among the native defects in ZnO, V Zn and O i act as acceptors. We then present the theory of p-type doping in ZnO, and summarize the growth techniques for p-type ZnO and the properties of p-type ZnO materials. Theoretically, the principles of selection of p-type dopant, codoping method and X Zn –2V Zn acceptor model are introduced. Experimentally, besides the intrinsic p-type ZnO grown at O-rich ambient, p-type ZnO (MgZnO) materials have been prepared by various techniques using Group-I, IV and V elements. We pay a special attention to the band gap of p-type ZnO by band-gap engineering and room temperature ferromagnetism observed in p-type ZnO. Finally, we summarize the devices based on p-type ZnO materials.

RaoP-Type ZnO Materials: Theory, Growth, Properties, and Devices

A summary is presented of the present status of several compound semiconductor radiation detectors, including detectors fabricated from GaAs, HgI2, CdTe, Cd1−xZnxTe and PbI2

Room-temperature compound semiconductor radiation detectors

Effect of disorder on the optical spectra of wide-gap II–VI semiconductor solid solutions

Solution hardening and dislocation density reduction in CdTe crystals by Zn addition

CdTe growth by ``multipass thm'' and ``sublimation thm''

A simple but tractable model of the density of exciton states associated with potential fluctuations in semiconductor alloys is proposed. It consists of minimizing the fluctuation entropy related to the composition fluctuation {Delta}{ital x} averaged over a volume {ital V}, for a given localization energy {var epsilon}. A critical volume {ital V}{sub {ital c}}({Delta}{ital x}), defined as the smallest volume in which the fluctuation {Delta}{ital x} can occur, is introduced. This model leads to a density-of-states tail of the form exp({minus}({var epsilon}/{var epsilon}{sub 0}){sup 3/2}). The characteristic energy {var epsilon}{sub 0} depends on the manner an exciton can be localized: as a whole or through electron and/or hole confinement. It is shown that the most probable event is determined by two physical parameters of the system: the electron-hole mass ratio and the ratio between the coefficients of variation with composition of the conduction- and valence-band edges. The density of states is used to model the exciton photoluminescence line shape of three representative alloys Zn{sub 0.97}Hg{sub 0.03}Te, CdS{sub 0.36}Se{sub 0.64}, and Cd{sub 0.92}Hg{sub 0.08}Te in which exciton localization occurs, respectively, via the electron, via the hole, or by electron-hole confinement. In each case a good agreement with the experimental results ismore » obtained.« less

Localized excitons in II-VI semiconductor alloys : density-of-states model and photoluminescence line-shape analysis

Systematic photoluminescence study of CdxHg1-xTe alloys in a wide composition range

The characteristics of defect and impurity centres which introduce near-mid-gap localized levels in CdTe are reviewed. Attention is focused on the 0.8–0.9 eV energy depth range corresponding to the wavelength range of optical telecommunications. The most appropriate centres are deep donors of group IV (tin, germanium) and transition metals (either deep donors (titanium, vanadium) or a deep acceptor (nickel)).

Y. Marfaing

Papers

Solution hardening and dislocation density reduction in CdTe crystals by Zn addition

CdTe growth by ``multipass thm'' and ``sublimation thm''

Localized excitons in II-VI semiconductor alloys : density-of-states model and photoluminescence line-shape analysis

Systematic photoluminescence study of CdxHg1-xTe alloys in a wide composition range

Deep centres for optical processing in CdTe