Spectrally dependent photocurrent measurements in n+-n-n+ heterostructure devices

Photocurrent measurements are shown to be a useful tool for characterizing charge-injecting heterostructure devices under bias. The measurements rely on a large photoconductive gain mechanism which operates in single-barrier, double-barrier, and superlattice devices. Photocurrent measurements on a set of superlattice doping interface devices indicate the presence of charge domains and an interesting electric field-screening phenomenon. These phenomena are not evident in the current versus voltage data and emphasize the importance of using optical probes to characterize electronic devices.