AIGaAs/GaAs V‐Groove channeled substrate buried heterostructure laser diodes

Abstract

Channeled substrate buried (CSB) heterostructure laser diodes have been developed successfully. To fabricate CSB lasers a two‐step liquid‐phase epitaxial (LPE) growth in conjunction with the standard etching techniques was required. The first step of the LPE process was to grow a p‐type GaAs internal current confining layer on the n‐GaAs substrate, followed by the etching of parallel V‐grooves along the [011] direction. The second LPE process was to grow a four‐layer laser structure over the V‐grooves. Due to the smoothing effect, an active layer with a crescent‐shaped cross section was formed. Because of the undercutting effect during the etching process, the active layer became very wide, i. e.,∼25μm. This resulted in a far‐field pattern along the junction plane with multifilaments. Each filament had a full angle at half maximun of 8∼10°. The smallest threshold current was found to be 0.88 A, which corresponds to a threshold current density of 8 KA/cm². Its mode profile was in the range of 8,360 Å to 8,400 Å.