Double channel planar buried heterostructure laser

DETAILED DESCRIPTION It is therefore an object of the present invention to provide a BH-LD in which blocking layers effectively function to enhance the temperature and output characteristics of the BH-LD to an unprecedented degree while also enhancing the reproducibility and yield of manufacture.
A semiconductor laser having a buried double heterostructure embodying the present invention includes a semiconductor substrate of a first conductivity type.
A multi-layer double heterostructure includes successively at least a first cladding semiconductor layer of the first conductivity type, an active semiconductor layer, and a second cladding semiconductor layer of a second conductivity type.
The active semiconductor layer has a narrower bandgap than those of the first and second cladding semiconductor layers.
The multi-layer double heterostructure has a stripe geometry with channels formed along both sides of the stripe and extending down to the first cladding layer.
A current blocking layer is formed on the multi-layer double heterostructure except for the top surface of the stripe geometry, in order to block a current flow therethrough.
A pair of electrodes supply a voltage to forward bias the semiconductor laser.
A p-n-p-n thyristor structure is generally analyzed using a model connection of a p-n-p transistor and an n-p-n transistor.
Concerning the characteristics of a thyristor itself, it is preferable that the thyristor turn-on voltage undergo a substantial change in response to a change in gate current.
This conflicts with the requirement that the turn-on voltage of a blacking layering in a semiconductor laser change little in response to a change in gate current.
Stated another way, a thyristor with poor performance is rather suitable for a blocking layer structure.
Such a thyristor is achievable by reducing the current gain of one or both of the p-n-p and n-p-n transistors.
It may roughly be said that the current gain of a transistor can be reduced by reducing the current carried by the minority carriers at the base relative to the total emitter current