Indirect barrier electron-hole gas transitions in mixed type-I-type-II GaAs/AlAs multiple quantum wells
15 July 2001
We studied the photoluminescence (PL) spectrum resulting of the indirect recombination of barrier electrons and the two-dimensional hole gas (2DHG) that is excited in a structure of mixed type-I-type-II GaAs/AIAs quantum wells. This structure consists of alternating narrow and wide GaAs quantum wells (QW), and is distinguished by a staggered conduction-band alignment that leads to a fast electron transfer from the narrow to the wide QW's and a very slow hole transfer. Consequently, a 2DHG and a two-dimensional electron gas (2DEG) are formed in the narrow and wide QW's, respectively. Their density is controlled by the photoexcitation intensity and is experimentally determined by fitting the band shape of the wide-well direct-recombination PL spectra (in the range of 10(10)