Microdisk lasers with a bridge contact pad formed by wet chemical etching

This study presents an approach for fabricating microlasers with quantum dots on GaAs substrates, featuring a disk resonator, a bridge-type electrical contact, and a supporting mesa structure formed by wet chemical etching. The influence of under-etched ledge in the disk cavity, formed under the metal bridge, as well as the low lateral current spreading due to small electrical contact area on the cavity surface was investigated. It was found that cleaving the under-etched ledge in the disk cavity significantly reduced the threshold current leading to the possibility to continuous-wave laser operation. The low lateral current spreading associated with small metal contact on the disk surface was confirmed by the spatially resolved electroluminescence studies in the cleaved half-disk microlasers.