Electrical characterisation of strained modulation doped In/sub x/Ga/sub 1-x/As/InP heterostructures with extremely high mobilities

It is shown that the mobility of modulation-doped In/sub x/Ga/sub 1-x/As/InP can be effectively increased by increasing the indium content in the channel up to a value of 77%. The carrier concentration also increased for higher indium contents due to more efficient carrier transport and confinement. Calculated mobilities for different indium contents are in good agreement with experimentally determined values. For indium contents higher than 77% the strained channel degenerates as the layer begins to relax. No conducting bypass channel was observed as shown by Shubnikov-de Haas and quantum Hall measurements. Due to the high electron mobilities even at room temperature, strained modulation doped In/sub x/Ga/sub 1-x/As/InP should find interesting applications in high-speed electronics, and because of the low effective electron mass it might also be attractive for studies in the quantum transport regime.<>