Transport properties of intrinsically and extrinsically modulation doped InP/InGaAs heterostructures

Transport properties in a new type of modulation doped InP/InGaAs systems, where the n-type doping is provided by intrinsic P-In-antisite defects rath er than foreign impurities, are studied by Shubnikov-de-Haas (SdH) oscillat ions and low-field Hall effect measurements. A close comparison of transpor t properties is made between these intrinsically modulation doped structure s with extrinsically doped structures, with the emphasis on two of the most important physical processes i.e. doping efficiency and scattering mechani sm. It is found that the efficiency of the intrinsic modulation doping is a t least as high as the extrinsic modulation doping. The mobilities of the t wo dimensional electron gas (2DEG) derived from Hall and SdH measurements a re shown to be higher in the intrinsically doped structures as compared to the extrinsically doped structures. This is attributed to a reduced scatter ing of the 2DEG by the remote parent dopants, due to e.g. an increased scre ening of the scattering potential by the excess free electrons present in t he intrinsic doping region due to auto-ionization of the P-In antisite.