VERTICAL CAVITY SURFACE EMITTING LASERS WITH ELECTRICALLY CONDUCTING MIRRORS

This invention is a semiconductor vertical cavity surface emitting laser comprising a lasing cavity with an active layer (14), a bottom (rear) mirror (12) and a top (front) mirror (17), and a front and rear electrodes (17,18) for applying excitation current in direction substantially parallel to the direction of optical propagation. In accordance with this invention the front mirror comprises a thin, semitransparent metal layer (17) which also acts as the front electrode. The metal layer is upon a highly doped layer (16) forming a non-alloyed ohmic contact. The metal is selected from Ag and Al and is deposited in thickness ranging from 5 to 55 nm. The VCSEL is a semiconductor device wherein the semiconductor material is a III-V or II-VI compound semiconductor. For a VCSEL with GaAs active layer, the light output from the front metal mirror/electrode side yields a high external differential quantum efficiency as high as 54 percent. This is the highest quantum efficiency obtained in VCSEL structures. Quantum efficiences on the order of 10 to 30 percent are typical for prior art VCSEL structures. The VCSEL is suitable for fabrication utilizing planar technology.