Showa Denko Kabushiki Kaisha

Junichi Yamamoto

Atsushi Yoshinaga

Akihiro Kitazaki

The present invention provides an epitaxial wafer which is obtained by sequentially forming, on an n-type GaAs substrate, a first n-type GaAlAs layer; a second n-type GaAlAs layer; an n-type GaAlAs cladding layer; a p-type GaAlAs active layer which has an emission wavelength of 850-900 nm; and a p-type GaAlAs cladding layer, through liquid phase epitaxy, and, subsequently, removing the n-type GaAs substrate. In the epitaxial wafer, the p-type GaAlAs cladding layer has a thickness of 5-30 &mgr;m; the p-type GaAlAs cladding layer has an oxygen concentration of 3&times;10 atoms/cm or less; the p-type GaAlAs cladding layer has a carrier concentration of 1&times;10 cm to 1&times;10 cm ; the p-type GaAlAs active layer has a thickness of 0.05-0.4 &mgr;m; the peak carbon concentration of the portion in the second n-type GaAlAs layer within 2 &mgr;m of the interface between the second n-type GaAlAs layer and the first n-type GaAlAs layer is less than 1&times;10 atoms/cm ; the p-type GaAlAs active layer contains germanium as a predominant dopant; the n-type GaAlAs cladding layer has a Ge concentration of 3&times;10 atoms/cm or less; and the second n-type GaAlAs layer has a Ge concentration of 3&times;10 atoms/cm or less. The invention provides an epitaxial wafer of double-hetero structure for producing high-intensity GaAlAs infrared LEDs.

Epitaxial wafer for infrared light-emitting device and light-emitting device using the same

The present invention provides an epitaxial wafer comprising, on a p-type GaAs single-crystal substrate, a first p-type layer; a p-type cladding layer; a p-type active layer; and an n-type cladding layer, wherein the n-type cladding layer has a carrier concentration of 1&times;10 to 1&times;10 cm ; a sulfur concentration of 3&times;10 atoms/cm or less; and a thickness of 20-50 &mgr;m. The maximum silicon concentration in the portion of the p-type cladding layer within 2 &mgr;m of the interface between the p-type cladding layer and the first p-type layer is less than 1&times;10 atoms/cm ; the concentration of carbon, sulfur, or oxygen in the first p-type layer is less than 1&times;10 atoms/cm ; the p-type cladding layer has a thickness of 50-80 &mgr;m; the first p-type layer has a carrier concentration of 3&times;10 to 1&times;10 cm ; and the n-type cladding layer contains germanium at a concentration of 3&times;10 cm or less. Thus, there can be produced an epitaxial wafer for fabricating an infrared LED exhibiting high emitted-light intensity with small variation.

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Saitama, Japan

Junichi Yamamoto