A simple way to reduce series resistance in p-doped semiconductor distributed Bragg reflectors

A novel method has been used to smooth out the energy band discontinuity at the heterojunction of AlAs and GaAs in quarter-wave distributed Bragg reflectors (DBRs) by linearly grading the Al and Ga compositions. This has been achieved by simply varying the cell temperatures of Al and Ga. No shutter operation was used during the MBE growth of these DBR mirrors. Low series resistance at a moderate doping (3 x 1018 cm-3) and high optical reflectivity have been obtained in the p-type DBRs using our approach. These p-DBRs were characterized by high-resolution X-ray diffraction, optical reflectivity, and electrical measurements. © 1991.