Semiconductor surfaces and interfaces

Semiconductor surfaces and interfaces

Semiconductor surfaces and interfaces R.H. WILLIAMS Vacuum 33 (10-12), 587 (1983) The development of modern techniques to probe surfaces on an atomic ...

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Semiconductor surfaces and interfaces R.H. WILLIAMS Vacuum 33 (10-12), 587 (1983) The development of modern techniques to probe surfaces on an atomic scale, coupled with parallel theoretical calculations of surface structures and electronic states has led to substantial progress in our understanding of semiconductor surfaces and their interfaces with 9metal contacts. Recent experiments are briefly reviewed and some recent theories relating to electrical barrier formation at metal-semiconductor interfaces considered. Carrier lifetime in (AI,Ga)As epilayers and double heterostructure lasers grown with metal-organic vapourphase epitaxy and liquid-phase epitaxy G.W.T. HOOFT, C. VAN ORDORP and A.T. VINK Acta Electron. 25 (3), 193 (1983) In French Carrier lifetime measurements on MO-VPE grown GaAs and Al~Gal.xAs (x ~<0.17) are reported and compared with similar data on LPE material. Two types of measurements are used. The first method is to study the decay of the band edge liminescence, as optically excited by the 647.1 nm radiation of a mode-locked Kr + laser, which yields the effective minority carrier lifetime Eeff at low excitation conditions ( A n , A p < n0,p0); that is, both the radiative and non-radiative part contribute to ett- The second method is a novel way of analysing efficiency and light-output data of double-heterostructure lasers operating in the spontaneous high-injection regime ( A n ~ A p > no,po). With this method~ the nonradiative part of the carrier lifetime can be obtained, even when the radiative recombination rate largely exceeds the non-radiative rate. No essential differences in carrier lifetime were found between MO-VPE and LPEgrown material. In GaAs, the value of ctf measured at low excitation densities apparently is limited by the radiative lifetime. The value of eft strongly decreases, however, with increasing AI content, showing that effective killer centres are incorporated both during LPE and MO-VPE. The i~ecombination through these centres shows saturation effects with increasing excitation densities. The non-radiative part of the carrier lifetime in the high-injection regime is discussed in terms of bulk and interface recombination. For one sample, the temperature dependence on the interface recombination velocity is presented. The results point to multiphonon processes being involved in the electron and hole capture by the interface killers.

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