Photosensitive devices and methods of making same

摘要

1,116,088. Photoelectric devices. TEXAS INSTRUMENTS Inc. 24 June, 1965 [26 June 1964], No. 26857/65. Heading H1K. A photo-sensitive device, which may utilize the photo-conductive, photo-voltaic or photoelectromagnetic effects, comprises a crystalline element which transmits radiation of a particular wavelength or wavelength band, and a monocrystalline photo-responsive portion sensitive to that particular wavelength or wavelength band formed on a surface of the transmissive element as an epitaxial extension of the element lattice. Electrodes are provided on the photo-responsive material. The transmissive element may be entirely monocrystalline or may be polycrystalline, but of sufficient optical quality and having a monocrystalline surface portion on which the photo-responsive layer is formed. Fig. 3 shows a photo-voltaic diode comprising a P-type layer 121 of indium arsenide formed either epitaxially on or by diffusing zinc or cadmium into a monocrystalline N-type layer 111 of indium arsenide epitaxially deposited on an N-type or intrinsic substrate 10 of gallium arsenide, which has a larger band gap (1.38 ev.) than that of the indium arsenide layer (0.33 ev.) so that the substrate is transparent to radiation operative on the PN junction. A plurality of diodes may be formed on the substrate. Fig. 7 shows a modification in which the Ga As substrate 201 is formed as a lens. The P-type In As layer 221 may be formed by diffusion or epitaxial deposition on to the N-type In As layer 21, and subsequent mesa formation by etching. The diode may be formed by planar techniques including oxide masking. A photo resistor comprising a layer of In As or Ge is also described. The transmissive substrate element may comprise an aplanatic or diffusing lens, or may include other optical elements such as reticles. The structure may also be formed with germanium on gallium arsenide, or indium arsenide on gallium antimonide.