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Double Junction Optical Semiconductor

IP.com Disclosure Number: IPCOM000091210D
Original Publication Date: 1969-Nov-01
Included in the Prior Art Database: 2005-Mar-05
Document File: 3 page(s) / 25K

Publishing Venue

IBM

Related People

Prusik, EW: AUTHOR [+2]

Abstract

Semiconductor 10 has PN diode junctions 11 and 12 which operate in the visible red and infrared spectra respectively. Junction 12 is formed by P and N regions 13 and 14 of GaAs. Junction 11 is formed by N and P regions 15 and 16 of GaAlAs. N region 14 is a substrate on which GaAlAs diode 15-16 is formed. A bias supply and switching devices, both not shown, are connected to electrodes 17 and 19 and selectively bias junctions 11 and 12 either individually or simultaneously or both.

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Double Junction Optical Semiconductor

Semiconductor 10 has PN diode junctions 11 and 12 which operate in the visible red and infrared spectra respectively. Junction 12 is formed by P and N regions 13 and 14 of GaAs. Junction 11 is formed by N and P regions 15 and 16 of GaAlAs. N region 14 is a substrate on which GaAlAs diode 15-16 is formed. A bias supply and switching devices, both not shown, are connected to electrodes 17 and 19 and selectively bias junctions 11 and 12 either individually or simultaneously or both.

When junction 11 is biased in the forward and reverse directions, it emits and senses, respectively, red light. Similarly, when junction 12 is biased in the forward and reverse directions, it emits and senses, respectively, infrared light. The semiconductor structure 10 is made by a method comprising several steps. In step a, a Ga solution of 20 gms., for example, is provided. In step b, there is added to the Ga solution, sufficient amount of GaAs compound polycrystal as small particles to supersaturate the Ga solution when the mixture is subsequently heated in step c, for example, 4.5 gms. of GaAs for 20 gms. of Ga solution. There is also added a predetermined amount of Al depending upon the desired red wavelength characteristic, e.g., adding Al within the range of 60 to 75 mg. for a corresponding range of 7000 angstroms to 6200 angstroms of red wavelength spectrum, respectively, and also adding an N-type dopant such as Te.

In step c, the mixture of step b is heated to a melt of 970 degrees C for approximately 20 minutes to supersaturate the GaAs crystal into the Ga solution and then there is cooling of the melt to 950 degrees C. For step d, there is immersion of an N-type GaAs wafer with only one of its planer surfaces exposed into the melt at 950 degrees C and a heating of the melt to a temperature of 958 degrees C to remove surface impurities from the exposed surface of the wafer which is in contact with the melt. In step e, the melt is cooled at 0.5 degrees C per minute from 958 degrees C until it reaches the temperature 910 degrees C to form the GaAlAs N region 15 from the exposed surface side of the wafer. For step f,...