The effect of the growth rate on the low pressure metalorganic vapour phase epitaxy of GaAs/Ge heterostructures

Anti-phase domain-free growth of GaAs on offcut (001) Ge wafers by molecular beam epitaxy with suppressed Ge outdiffusion

“…23 The strain fields associated with these misfits produce characteristic crosshatching surface undulations along in-plane <110> directions which are clearly observable via AFM and which also are faintly visible via Nomarski phase contrast optical microscopy. 11,24 We have found that for thick films, the observable crosshatching surface undulations strongly correlate with very minimal or non-existent APD disorder as characterized by TEM. Since the crosshatch results from aggregates of long misfit segments which in turn result from glide of threading dislocations over long distances, this relationship between crosshatch and APD disorder indicates that the APDs block dislocation glide.…”

“…In previous GaAs growth studies on Ge wafers by both MBE 26,27 and by MOCVD, 24 it has been observed that Ge outdiffusion produces very high n-type doping in the GaAs films, sometimes in the 10 18 cm -3 range. This is an important problem that impacts control of doping profiles, junction formation, and optimum buffer layer thicknesses for device applications.…”

Scanning force microscopy studies of GaAs films grown on offcut Ge substrates

“…The crosshatch lines are directly related to the presence of these misfit dislocations. 13 In one direction, there is only one set of parallel lines. In the perpendicular direction, the Fig.…”

Interface states density distribution in Au/n-GaAs Schottky diodes on n-Ge and n-GaAs substrates

“…A diode structure consisting of Au/n-GaAs over Ge often gives a higher ideality factor, lower barrier height, and a soft breakdown voltage due to the misfit dislocations formed inside the GaAs substrate during the heteroepitaxial growth process [1]. Unless the MOVPE growth parameters are precisely controlled, the epi-GaAs over Ge often gives antiphase domains and misfit dislocations, which gives rise to poor electrical transport characteristics [2][3][4][5][6][7]. In fact, the grown GaAs epilayer over Ge might contribute to the high density of surface states, which increases the surface recombination velocity, decreases the minority carrier lifetime, and increases the leakage at the junction, all of which worsening the GaAs/Ge solar cell performance [6,7].…”