Current Applied Physics, Vol.19, No.10, 1132-1135, 2019
Raman study of InAs/GaAs quantum dot solar cells
We report polarized and resonant Raman study of InAs/GaAs quantum dot solar cell (QDSC) structures. Raman spectra obtained from the top surfaces of the samples suggested that the formation of InAs QDs induced tensile strain in the overgrown GaAs layers. Furthermore, a longitudinal optical phonon-plasmon (LPP) coupled modes were observed in the p-type GaAs layers. The tensile strain was increased with an increase in the QD size. The hole concentrations estimated by fitting the individual LPP coupled modes were in the range of 2.4-3.5 x 10(18) cm(-3). Resonant Raman spectra obtained from the cleaved sides, where the QDs were located, showed a 225 cm(-1) mode in parallel polarization configurations. Based on accurate analysis, this mode was identified as the LA(X) phonon of GaAs.