Ryan E. Doezema
B.A. 1964 Calvin College
Ph.D. 1971 Maryland

My research interests center on the magneto-electronic properties of semiconductors. The work is focused on the lower-dimensional electron systems formed in synthetically created quantum wells and superlattices Photonic transitions between quantum levels in the wells, and between magnetic levels induced by strong external magnetic fields, are studied using both a far-infrared, optically-pumped laser system as well as a Fourier transform infrared spectrometer. Our goals include the determination of electron dispersion as well as relaxation processes

We are especially interested in novel properties of quantum-well systems caused by band structure effects such as mass-mismatch and extreme non-parabolicity. Our work is made possible by the flexibility for designing quantum-well systems with the MBE system as part of the Center for Semiconductor Physics in Nanostructures (C-SPIN). Our experiments concentrate on the narrow-gap system InSb which, as a quantum well material, shows much promise for infrared and laser devices. We have been able to determine the defining characteristics of the binding potentials for these quantum wells (gap mismatch and band offset). Especially exciting is our recent observation of spin resonance in this system and, in asymmetric wells, evidence of spin splitting in zero magnetic field because of strong spin-orbit coupling

N. Dai, F. Brown, R.E. Doezema, S.J. Chung, K.J. Goldammer, and M.B. Santos, ``Determination of the Concentration and Temperature Dependence of the Fundamental Energy Gap in $\rm Al_xIn_{1-x}Sb$,'' Appl. Phys. Lett., 73, 3132 (1998).

N. Dai, G.A. Khodaparast, F. Brown, R.E. Doezema, S.J. Chung, and M.B Santos, ``Band Offset Determination in the Strained-Layer $\rm InSb/Al_xIn_{1-x}Sb$ System," Appl. Phys. Lett. 76, 3905 (2000).

G.A. Khodaparast, S.J. Chung, R.E. Doezema, and M.B. Santos, ``Energy Probe of the Rashba Spin Splitting in Heterostructures," submitted for publication.