Electron transport in Sb-doped metalorganic epitaxial GaAs grown at moderate As-rich conditions

Abstract

The influence of antimony incorporation in GaAs metalorganic vapor phase epitaxial (MOVPE) layers has been investigated. The results obtained concern the behavior of the carrier concentration (n) and the mobility (μ) developed from Hall effect measurements. In order to achieve a reliable quantitative interpretation the samples studied have been grown at a moderate V/III ratio which ensures n-type conductivity and does not favor SbGa heteroantisite defect formation. Three regions of specific influence of Sb doping on the electrical parameters have been distinguished. For Sb mole fraction in the input gas phase (MFTMSb) ranging between 0 and 6×10−6, n slightly decreases, while the mobility sharply increases compared with undoped layers. This is discussed in terms of electrically active and neutral As vacancies. The quantitative consideration of the scattering mechanism offers the possibility of correcting the compensation ratio in the undoped GaAs samples determined by commonly used procedures. The n and μ dependences at higher Sb doping have been related to residual amphoteric impurity redistribution between Ga and As sublattices. In the heavily doped region the effect of the charged Ga vacancies has been involved. It has been shown that the Sb incorporation in the optimum concentration limits leads to an improvement of the electrical characteristics of MOVPE GaAs layers.