Buried mesa semiconductor device

Abstract

The present invention relates to a buried mesa semiconductor device such as a laser diode with reduced leakage currents past the heterojunction, and to a method of forming such a device. The method comprises the steps of: growing a semiconductor wafer (1) with a plurality of layers including a substrate (2) and an active layer (6); depositing a mask (52) on the wafer (1) which defines one or more mesa regions (51); etching the wafer (1) to remove semiconductor layers to form a mesa structure (51) above the substrate (2), each mesa region (51) having mesa sides (53,54) extending upwards from the substrate (2) and between the mesa sides (53,54) a mesa top (63,64,65); growing one or more current confining semiconductor layers (56A,59A) to cover the mesa sides (53,54); removing part of the mask (52) along a part (64,65) of the top of the mesa adjacent the mesa sides (53,54); growing a leakage current confining semiconductor layer (68A) on a previous current confining layer (59A) so that the leakage current confining semiconductor layer (68A) extends to overlie partly (64,65) the mesa top adjacent said mesa sides (53,54); and removing the residual mask (62) and growing above the mesa top (63,64,65) one or more electrical contact semiconductor layers (75) by which a confined electrical current may be applied through the mesa (51) and substrate (2).

Dependencies are inferred from the claim text.