STUDY OF INALAS/INGAAS HETEROJUNCTION BIPOLAR-TRANSISTOR LAYERS BY OPTICALLY DETECTED CYCLOTRON-RESONANCE

We report an investigation of optical and electronic properties in InAlAs/InGaAs heterojunction bipolar transistor layers by optical detection of cyclotron resonance (ODCR). Strong ODCR spectra structured by quantum oscillations have been observed, from which the effective mass and the carrier concentration of the two‐dimensional electron gas can be obtained. The measured cyclotron mass is heavier than the conduction‐band‐edge mass in bulk InGaAs. We find that the carrier concentration increases with the spacer thickness. Quite unexpectedly, we also find that the effective mass increases with decreasing the carrier concentration. © 1995, American Institute of Physics. All rights reserved.