Tunable all epitaxial semimetal-semiconductor Schottky diode system: ErAs on InAlGaAs
Schematic diagram showing typical layer structure and device cross section.
Current density plotted against voltage for compositions (a) varying from InGaAs , which is nearly Ohmic, to InAlAs , which has traditional Schottky-type behavior plotted over a large voltage range, and (b) samples ranging from to showing detail near zero-bias.
Schottky barrier height as extracted from measurements, 엯, and as extracted by measurements, ●. The error bars represent possible error in the assumed Richardson constant.
Zero-bias differential resistance of the junction is plotted against composition, showing the expected exponential behavior. Values as-measured and with series resistance subtracted are shown.
Doping levels in the semiconductor drastically change the reverse bias characteristics of the diode, while forward bias characteristics are relatively unchanged. Data are shown for diodes with and silicon doping is given in units of .
Capacitance, plotted against the square root of Si depletion-region doping density, shows the expected linear dependence. Data is shown for diodes with .
Differential resistance plotted against Si doping concentration for diodes with . The primary difference is due to the effects of doping on reverse-bias breakdown.
(a) curve of a diode is plotted with the corresponding responsivity. The peak responsivity is at zero bias, is negative for reverse bias greater than , and series resistance dominates the behavior at forward voltages greater than , reducing responsivity to almost zero. (b) The maximum short-circuit responsivity, calculated from dc curves, is plotted against composition; this quantifies the rf rectification expected from the diodes.
Varying the interface composition changes the barrier height of the diode. The semiconductor is , but the last monolayer deposited is altered. The interface composition is designated by the last semiconductor deposited. This results in a change in barrier height, differential resistance, and short circuit responsivity.
Short circuit responsivity for a frequency of through , for the square device with , showing both actual rectified current (circles) and the values calculated by numerically removing the impedance mismatch (line).
Summary of relevant layer thickness and composition. The - doping and thickness are designated for the depletion layer and the UID thickness is the unintentionally doped layer thickness.
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