Showa Denko K.k.

Showa Denko Kabushiki Kaisha

Atsushi Yoshinaga

Junichi Yamamoto

Koichi Hasegawa

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.

The invention provides an epitaxial wafer including a first p-type layer; a p-type cladding layer; a p-type active layer; an n-type cladding layer; and a second n-type layer stacked on a p-type GaAs single-crystal substrate, wherein Zn is employed as a dopant in the first p-type layer; Ge is employed as a dopant in the p-type cladding layer and the p-type active layer; Te is employed as a dopant in the n-type cladding later and the second n-type layer; the average carrier concentration of the n-type cladding layer and the second n-type layer is 8&times;10 cm to 2&times;10 cm ; the n-type cladding layer has a thickness of 60-80 &mgr;m; the second n-type layer has a total concentration of Zn and Ge of 1&times;10 atoms/cm or less; the dopant concentration of the portion in the second n-type layer within 3 &mgr;m of the interface between the n-type cladding layer and the second n-type layer is 3&times;10 cm or more; the Al compositional proportion in the n-type cladding layer or the second n-type layer is 0.10-0.35; the p-type active layer has a thickness of 0.5-1.2 &mgr;m; and the p-type active layer has an oxygen concentration of less than 3&times;10 atoms/cm . Epitaxial wafers for fabricating high-intensity and long-service-life GaAlAs infrared light-emitting devices are provided.

A GaP green light-emitting diode includes an n-type GaP single-crystal substrate on which is formed at least an n-type GaP layer, a nitrogen-doped n-type GaP layer and a nitrogen-doped p-type GaP layer. The concentration of carbon and/or sulfur in the nitrogen-doped n-type GaP layers is controlled to be not more than 6.times.10.sup.15 cm.sup.-3.

Gallium phosphide green light-emitting device

An epitaxial structure for a GaP light-emitting diode comprises an n-type GaP single crystal substrate on which is formed a plural buffer layer epitaxially grown on the single crystal substrate, in which the buffer layer has a lower etch pit density than the etch pit density of the single crystal substrate, etch pit density decreases with each upper layer, and a GaP active layer is formed on the buffer layer.

Epitaxial structure for GaP light-emitting diode

An epitaxial wafer for a GaP light-emitting element comprising an n-type GaP buffer layer, n-type GaP layer, nitrogen-doped n-type GaP layer and p-type GaP layer grown sequentially on an n-type GaP single-crystal substrate, in which the sum concentration of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu in the nitrogen-doped n-type GaP layer does not exceed 1.times.10.sup.15 cm.sup.-3, and the sum concentration of Ti, V, Cr, Mn, Fe, Co, Ni, and Cu in the buffer layer does not exceed 1.times.10.sup.16 cm.sup.-3. n-type and p-type electrodes are formed on the wafer which is then divided to form GaP light-emitting elements.

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Saitama, Japan

Atsushi Yoshinaga