ISSN:
1089-7550
Source:
AIP Digital Archive
Topics:
Physics
Notes:
The momentum conserving indirect excitonic transitions, from the Γ15 valence band maximum to the conduction band minima close to the X1 point in the Brillouin zone have been measured for GaP in piezo-modulated transmission. At 6 K, excitonic signatures due to phonon emission are observed at Egx+(h-dash-bar)ωph for TA(X), LA(X), and TO(X) phonons (Egx=free exciton band gap), whereas at 120 K signatures for both absorption and emission of LA(X) and TA(X) phonons appear. These observations yield Egx=2.3301(4) eV at 6 K. In several GaP specimens, signatures A and/or C for excitons bound to sulfur (S) and/or nitrogen (N) impurities, respectively, are observed in the piezo-modulated transmission. A parallel investigation of the spectra of recombination radiation reveals emission lines for excitons bound to S and N as well as their phonon sidebands. The phonon replicas of N consist of sharp lines in combination with the zone center optical phonons observed in the first order Raman spectrum (LOΓ and TOΓ). In addition, broader replicas are observed for the A line in combination with acoustic and optical phonon branches (A-LA, A-TA, A-X). The phonon energies obtained from both piezo-modulation and photoluminescence experiments are compared with those reported in the literature. Finally, the suppression of S diffusion from a GaP substrate into a GaP epilayer achieved with an intervening GaP/AlGaP superlattice is demonstrated in both modulation and photoluminescence experiments. © 1997 American Institute of Physics.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1063/1.366241
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