ELECTROCHEMICALLY INDUCED ASYMMETRICAL ETCHING IN INALAS INGAAS HETEROSTRUCTURES FOR MODFET GATE-GROOVE FABRICATION/

We have achieved a self-controlled asymmetrical etching in metalorgani c chemical vapor deposition-grown InAlAs/InGaAs heterostructures, whic h can be suitable for fabricating modulation-doped field-effect transi stors (MODFETs) with gate-groove profiles for improved performance. Th e technology is based on electrochemical etching phenomena, which can be effectively controlled by using different surface metals for ohmic electrodes. When surface metals of Pt and Ni are deposited on the sour ce and the drain, respectively, the higher electrode potential of Pt r esults in slower etching on the source side than on the drain side. Th us, asymmetry of gate grooves can be formed by wet-chemical etching wi th citric-acid-based etchant. This represents a new possibility to con duct ''recess engineering'' for InAlAs/lnGaAs MODFETs.