Abstract A semiconductor device of certain p-type materials, such as indium antimonide (InSb), is capable of impact ionization initiated by injection of electrons if maintained within a certain temperature range, e.g., 50*- 120* K. A long npp+ InSb diode is maintained in a controlled temperature environment at 77*K. An external biasing source reverse biases the diode''s p+-p junction to block injection of electrons from the source and creates a relatively high electric field within the diode. When electrons are optically injected into the cathode end of the diode adjacent the p+-p junction by, for example, exposing the cathode region to infrared radiation, they initiate an impact ionization wave which travels the length of the diode in the very short time. When the impact ionization wave reaches the diode''s anode, the resultant current through the diode is many times higher than the current initiated by the photoelectric effect without impact ionization. This current is used to signify fast detection of infrared radiation in small quantities and may also be used, in conjunction with the known applied electric field, to indicate the amount of incident radiation.
An apparatus as recited in claim 1, wherein said p-type material is indium antimonide.
Claim 2
Dependent Claim
31 words
An apparatus as recited in claim 2, wherein said p+-type cathode region comprises an alloy of cadmium and indium, and said n-type anode region comprises an alloy of tellurium and indium.
Claim 3
Dependent Claim
31 words
An apparatus as recited in claim 2, wherein the magnitude of said biasing voltage is sufficient to produce an average electric field strength within said p-type material greater than 300 volts/cm.
Claim 4
Dependent Claim
15 words
An apparatus as recited in claim 1, wherein said p-type material comprises mercury cadmium telluride.
Claim 5
Dependent Claim
15 words
An apparatus as recited in claim 1, wherein said p-type material comprises lead tin telluride.
Claim 6
Dependent Claim
25 words
An apparatus as recited in claim 1, wherein said source means comprises a pulse generator periodically pulsing said semiconductor diode means with said biasing voltage.
Claim 7
Dependent Claim
27 words
An apparatus as recited in claim 1, wherein said p+-type cathode region is optically transparent to thereby expose an end of said p-type material to radiant energy.
Claim 8
Dependent Claim
29 words
An apparatus as recited in claim 1, wherein said source means provides a selectively variable magnitude of said biasing voltage to thereby control the response time of said apparatus.
Claim 9
Dependent Claim
26 words
An apparatus as recited in claim 1, wherein said p+-type cathode region defines a window exposing the cathode end of said p-type material to radiant energy.
Claim 10
Dependent Claim
26 words
An apparatus as recited in claim 10, wherein said p+-type cathode region is formed in an annular ring having an interior aperture exposing said cathode end.