Patents by Inventor Achyut Kumar Dutta

Achyut Kumar Dutta has filed for patents to protect the following inventions. This listing includes patent applications that are pending as well as patents that have already been granted by the United States Patent and Trademark Office (USPTO).

  • Patent number: 5861636
    Abstract: Disclosed is a surface emitting visible light emitting diode, which has: a first conductivity-type substrate; and a first conductivity-type buffer layer, a first conductivity-type cladding layer, an active layer, a second conductivity-type cladding layer, a second conductivity-type current spreading layer and a second conductivity-type cap layer which are in turn grown on the substrate; wherein the second conductivity-type cap layer has a ring shaped electrode formed thereon.
    Type: Grant
    Filed: April 11, 1996
    Date of Patent: January 19, 1999
    Assignee: NEC Corporation
    Inventors: Achyut Kumar Dutta, Akira Suzuki
  • Patent number: 5821569
    Abstract: An n-type GaAs layer as a buffer layer, an n-type (Al.sub.0.7 Ga.sub.0.3).sub.0.5 In.sub.0.5 P layer, an active layer, a p-type (Al.sub.0.7 Ga.sub.0.3).sub.0.5 In.sub.0.5 P layer, a thin layer of Al.sub.x Ga.sub.1-x As layer (x.gtoreq.0.9), an Al.sub.0.7 Ga.sub.0.3 As layer as a current spreading layer and a high doped p-type GaAs cap layer are sequentially grown on an n-type GaAs layer of a substrate. As the active layer, an (Al.sub.x Ga.sub.1-x).sub.0.5 In.sub.0.5 P based bulk or multi-quantum well is employed. As the current spreading layer, an Al.sub.x Ga.sub.1-x As (x.gtoreq.0.7) is employed. The current spreading layer is a p-type III-IV compound semiconductor having wider band gap than a band gap of a material used for forming the active layer, and being established a lattice matching with the lower p-type cladding layer. After mesa etching up to the cladding layer, growth of selective oxide is performed at a part of the AlGaAs layer. BY this, a block layer (selective oxide of AlGaAs) is formed.
    Type: Grant
    Filed: September 4, 1996
    Date of Patent: October 13, 1998
    Assignee: NEC Corporation
    Inventor: Achyut Kumar Dutta