Semiconductor laser with double heterostructure - made from gallium arsenide and gallium aluminium arsenide, has low threshold value

摘要

Laser has a monocrystal substrate(s) covered by an n-type confinement layer (1), then an active layer(2) of p-type GaAs, followed by a p-type confinement layer(3), and a p-type contact layer(4). Layers(3,4) are neutralised by proton bombardment except along a thin ribbon at the centre of the structure; but this neutralisation does not reach layer(2), which has a high dopant concn. whereas layer(3) has a low dopant concn. Substrate(S) is pref. n-GaAs with layer(1) of n-Ga1 AlxAs; and layer(2) is p-Ga1-yAlyAs. Layer(3) is pref. p-Ga gamma-zAlzAs; whereas layer(4) is p-GaAs. Layer(2) is pref. doped to above 3x10 17 atoms/cc, but layer(4) is doped to below 5x1017/cc. The dopant used in both layers (2,3) is pref. Ge; and z is pref. above 0.4 in layer(3). Used for optoelectronics, esp. optical telecommunications, where a threshold current of 45 mA can be obtd.