Recently
developed compound semiconductor GaInNAs is a promising material for optical
fiber communication. The absorption spectrum of thin GaInNAs layer (10-nm
thickness) was observed by using our developed piezoelectric photothermal
spectroscopy (PPTS). Although the effcet of a surface photo-induced voltage
could not be well separated, the spectra revealed step-like density of states
and exciton formation in two-dimensional discrete levels in the quantum
well. Effective mass of the conduction band was estimated to be 0.05m0 by
assuming that the valence band offset was negligible. Rapid thermal annealing
relaxes a lattice defects and distortions and this results in a blue shift
of the spectrum.
(APL 2003)
(APL, JJAP, EMRS2004�,
ISDRS2003, CPAC, etc.)