Variable-gap AlxGa1–xAs heterostructure for an electron-beam-pumped laser
A variable-gap (graded) heterostructure based on a p-type AlxGa1–xAs solid solution was used in a laser pumped transversely by an electron beam. The structure consisted of an AlxGa1–xAs (x≈0.2) buffer layer on a GaAs substrate, an active GaAs layer, and a solid-solution layer of variable composition ( 0.1 x 0.3) with the band gap increasing toward the surface. A method was developed for fabricating one layer by forced cooling of a saturated Ga–Al–As molten solution, containing Si as a p-type impurity present in a concentration [p] = (3–5)×1017 cm−3, and the other layers by isothermal mixing of two solutions characterized by different Al concentrations. A study was made of the parameters of the finished lasers operating at T = 300 K.