The Ge-ZnSe heterojunction has been prepared by vacuum evaporation of the ZnSe onto single-crystal p-type germanium substrates.' The growth conditions have been studied in terms of epitaxial growth on different crystallographic orientations in degrees of vacuum down to the ultra-highvacuum region. Measurements have also been made of the electrical characteristics, capacitance properties, and photoelectric response of the diode. From these measurements a realistic band model has emerged involving intrinsic and extrinsic defects present in the bulk and interfacial region of the zinc selenide. The results of this investigation are compared with those from devices grown by vapour phase epitaxy283 and the data presented suggests that a Mott-type barrier4 rather than a Schottky barrier is present at the germanium-zinc-selenide interface. Techniques have been developed for the removal of this Mott barrier and the resulting change in the physical properties and band structure will be given. Possible applications of heterojunctions with this particular band structure will be discussed. 295, 1968. ', N.M. Schottky-barrier diodes of chromium on n-type epitaxial gallium arsenide phosphide (GaAsP) were studied from 25" to 440°C. The diodes showed significant rectification properties up to a temperature of 440°C. At high temperature the reverse leakage current was 1.15 milliamperes at 25 volts with a diode area of 1.14 X 10-3 cm2 as compared with 0.25 microampere at room temperature.The chromium was evaporated from a tungsten filament in a vac-ion system at a pressure of less than 10-8 Torr. Silver was alloyed into the GaAs substrate to provide a good ohmic contact over the entire temperature range. The epitaxial layer was 200 Hm thick.The slope of the In current versus voltage curves was l.lkT/q. The barrier height for the chromium contact was 1.15 eV from the capacitancevoltage measurements and 1.05 eV from the current-voltage measurements.From the plot of ln(JJT2) versus 1/T, where J, is current density and T is temperature, the effective Richardson constant for these diodes is approximately 2.5 A/crnz/'KZ. The calculated value of carrier concentration from the capacitance-voltage curves was 8 X 1015/cm3. The reversebreakdown voltage of the diodes was in excess of BO volts a t room temperature. 146

No abstract

When Government drawings, specifications, or other data are used for any purpose other than in connection with a definitely Government-related procurement, the United States Government incurs no responsibility or any obligation whatsoever. The fact that the Government may have formulated or in any way supplied the said drawings, specifications, or other data, is not to be regarded by implication, or otherwise in any manner construed, as licensing the holder, or any other person or corporation; or as conveying any rights or permission to manufacture, use, or sell any patented invention that may in any way be related thereto.

No abstract

This paper describes the computer simulation of a hybrid infrared focal plane array (IRFPA) readout multiplexer. The device under study is a switched field effect transistor (SWIFET) readout multiplexer that utilizes a source follower per detector (SFD) unit cell amplifier. The objective of this study is to determine if the limiting component of the IRFPA nonlinearity is the infrared detector array or the readout multiplexer. This study was performed by developing a computer simulation within which the material, fabrication, and operational parameters of the SE) readout multiplexer could be varied. The computer simulation is able to predict experimental data from a SE) readout multiplexer thereby providing validation that the device models used in the computer simulation are correct.The most significant result determined by this study is that the nonlinearity associated with the SE) readout multiplexer is approximately an order of magnitude lower than the nonlinearity from a state-of-the-art PtSi infrared detector array. The nonlinearity in the SE) readout multiplexer is dominated by the body-effect in the source follower amplifiers that comprise the SE) readout multiplexer.