| 摘要 |
Light emitting devices require 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 (52) and a conductive substrate (51). Furthermore, a light absorbing layer is disposed on one side of a an unetched portion of the semi-insulating material (53) and an active layer (58) disposed on an opposite side of the unetched portion. Also, the interface of the semi-insulating material (53) and the active (58) 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 material etched to reveal a predetermined crystalline plane. <IMAGE> <IMAGE> |
