Method of fabricating semiconductor light emitting devices

Abstract

Light emitting devices are requiring greater switching speeds to achieve greater modulation bandwidths. The problems of intrinsic capacitance associated with conventional semiconductor heterojunction devices are reduced by the reduction of pn junction capacitance as well as the use of a semi-insulating blocking layer and a conductive substrate. Furthermore, a light absorbing layer is disposed on one side of an unetched portion of the semi-insulating material and an active layer disposed on opposite side. Also, the interface of the semi-insulating material and the active and absorbing layers are at prescribed angles that reduce back reflections to the absorbing and active layers. This arrangement reduces pumping in the absorbing region and thus reduces the lasing effect, allowing for a stable LED. The angle at the interface is determined by having the structure at a predetermined crystallographic direction and having the semi-insulating mesa etched to reveal a predetermined crystalline plane. Finally, in one embodiment of the invention, a channel is etched and filled with thermally conductive material to dissipate heat. This channel, in addition to the heat dissipation effected by the semi-insulating material enables a near linear light output versus current input characteristic for the device.