EDUCATION
A.B., Bowdoin College (1960)
Ph.D., Brown University (1966)

FOCUS

I am primarily interested in the basic physics and applications of semiconductor nanostructures. Within this rather broad and rapidly expanding area, my specific interests are the effects of confinement on impurities and defects, electron-electron and electron-hole interactions in low-dimensional systems, nonlinear spectroscopy of electronic states to obtain carrier lifetimes and other information, the effects of high pressure on electronic states of semiconductor nanostructures (with Professor B. A. Weinstein), and how reduced dimensionality affects the electron­optical phonon interaction. I employ far infrared spectroscopy, free electron lasers at Vanderbilt University and the University of California at Santa Barbara, a combination of far infrared and near infrared photoluminescence called optically detected resonance spectroscopy (with Professor Athos Petrou), and electrical transport techniques at low temperatures and high magnetic fields to obtain information on the electronic and optical properties of these systems.

SELECTED PROJECTS

• Spectroscopy and magnetotransport studies of InAs/AlGaSb heterostructures: search for stable, spatially separated correlated electron-hole state
• Effects of impurity ions on many-electron states in GaAs/AlGaAs quantum wells in high magnetic fields
• Optically detected resonance studies of free carriers, impurities, and excitons in low-dimensional semiconductor systems
• Lifetimes of quantized electronic states in low-dimensional semiconductor structures from free electron laser saturation spectroscopy
• High-pressure studies of shallow and deep impurity states in semiconductor heterostructures

PUBLICATIONS

• Z. X. Jiang, B. D. McCombe, and P. Hawrylak. Donor impurities as a probe of electron correlations in two-dimensional electron gas in high magnetic fields. Phys. Rev. Lett. 81:3499­502 (1998).
• Y. J. Wang, H. A. Nickel, B. D. McCombe, F. M. Peeters, J. M. Shi, G. Q. Hai, X. G. Wu, T. J. Eustis, and W. Schaff. Resonant magnetopolaron effect due to interface phonons in GaAs/A1GaAs multiple quantum well structures. Phys. Rev. Lett. 79:3226­29 (1997).
• M. S. Salib, H. A. Nickel, G. S. Herold, A. Petrou, B. D. McCombe, R. Chen, K. K. Bajaj, and W. Schaff. Observation of internal transitions of excitons in GaAs/AlGaAs quantum wells. Phys. Rev. Lett. 77:1135 (1996).
• J.-P. Cheng, J. Kono. B. D. McCombe, I. Lo, W. C. Mitchel, and C. E. Stutz. Evidence for a stable excitonic ground state in a spatially separated electron-hole system. Phys. Rev. Lett. 74:450 (1995).
• B. D. McCombe and A. Petrou. Optical properties of semiconductor quantum wells and superlattices. Handbook of Semiconductors, vol. 2, ch. 6, pp. 285­384, M. Balkanski ed. (Elsevier Science Publishers, Amsterdam, 1994).

Fig. 1 Optically detected resonance spectra of a Si-doped GaAs/AlGaAs quantum well structure. The peaks and valleys represent changes in the photoluminescence induced by absorption of 118.8 micron laser radiation, which excites internal transitions of shallow donor impurities and electron cyclotron resonance. The magnetic field is increasing from back to front and the photon energy from left to right.