Electro-Optical Investigations of Selectively Doped Heterostructure Transistors (SDHT's)

Using large area GaAs-AlGaAs SDHT's with transparent gate electrodes we studied the reflectivity spectra as a function of the applied gate voltage. We observe modulation of the reflectivity at the bandgaps of both materials, reaching 0.4% at the bandgap of AlGaAs, when the SDHT is tuned between the states "off" and "on" (electron concentration 0 to 5 x 10 cm sup -2).