ROOM-TEMPERATURE PHOTOREFLECTANCE CHARACTERIZATION OF INALAS INGAAS HETEROJUNCTION BIPOLAR-TRANSISTOR STRUCTURE INCLUDING 2-DIMENSIONAL ELECTRON-GAS/

Using contactless photoreflectance at 300 K we have characterized two InAlAs/InGaAs heterojunction bipolar transistor structures grown by mo lecular beam epitaxy. The spectra from the InAlAs and InGaAs interface can be accounted for on the basis of a triangular potential well whic h confined two-dimensional electron gas. A detailed lineshape fit make s it possible to evaluate the Fermi energy, and hence the two-dimensio nal electron gas concentration. Furthermore, other important parameter s of the system, such as built-in electric fields and In composition, can be evaluated.