Real-space charge-transfer device and method thereof
A real-space charge-transfer device is disclosed. In particular, a Gunn diode is disclosed having a conductive structure fabricated overlying its active region. A secondary signal, other than the normal Gunn diode signal, is generated by the Gunn diode based upon a characteristic of the overlying conductive structure. For example, when the conductive structure is a grate having N teeth the secondary signal will have N secondary oscillation cycles that occur during the duration of a single normal Gunn diode oscillation cycle.
1. A device comprising:
a real-space charge-transfer device comprising
a first anode/cathode terminal spaced apart by a first instance from a second anode/cathode terminal;
a semiconductor region coupled to the first and second anode/cathode, wherein current is to flow between the first anode/cathode terminal and the second anode/cathode terminal through the semiconductor region; and
a conductive structure overlying the semiconductor region, the conductive structure being spaced apart from the semiconductor region by less than 2500 Angstroms and having a conductivity that is greater than the conductivity of the semiconductor region; and
a filter comprising an input coupled to the second anode/cathode terminal, and an output, the filter configured to selectively pass a frequency component provided by the real-space charge-transfer device during operation that is based upon a characteristic of the conductive structure.
2. The device of claim 1 , wherein the entire length of the semiconductor region is n-doped.
3. The device of claim 1 , wherein the conductive structure comprises a number of repetitive features, and the characteristic of the conductive structure is the number of features.
4. The device of claim 1 , wherein the conductive structure comprises a first conductive tooth overlying a portion of the semiconductor region, a length of the conductive tooth being less than a length of the real-space charge-transfer device, and the characteristic of the conductive structure includes the length of the conductive tooth.
5. The device of claim 4 , wherein the conductive structure further comprises a grate comprising a plurality of conductive teeth that includes the first conductive tooth, and the characteristic of the conductive structure further comprises the number of teeth of the grate.
6. The device of claim 1 , wherein the plurality of repetitive features is a two-dimensional array of the features.
7. The device of claim 1 , wherein the conductive structure is a passive conductive structure.
8. A method of generating a signal comprising:
applying a voltage across a semiconductor region of a real-space charge-transfer device;
generating, in response to the voltage, a normal real-space charge-transfer signal at the semiconductor region, the normal real-space charge-transfer signal having a first fundamental frequency; and
generating, in response to the voltage, a secondary signal at the compound semiconductor region concurrently with the normal real-space charge-transfer signal, the secondary signal having a second fundamental frequency that is greater than the first fundamental frequency;
receiving the normal real-space charge-transfer signal and the secondary signal at a filter;
filtering the input signal to produce an application signal that oscillates at a frequency associated with the secondary signal.
9. The method of claim 8 , wherein the application signal includes the second fundamental frequency of the secondary signal.
10. The method of claim 9 , wherein the application signal does not include the first fundamental frequency of the normal real-space charge-transfer signal.
11. The method of claim 8 , wherein the application signal includes a harmonic of the fundamental frequency of the secondary signal.
12. The method of claim 8 , wherein the second fundamental frequency is based upon a characteristic of a conductive structure overlying the compound semiconductor region.
13. The method of claim 12 , wherein the characteristic is a number of conductive features of the conductive structure overlying the semiconductor region.
14. The method of claim 13 , wherein the characteristic is a spacing of individual conductive features of the conductive structure.
15. The method of claim 12 , wherein the characteristic is a number of conductive features of the conductive structure overlying the semiconductor region, and a spacing between the conductive features.
16. The method of claim 12 , wherein the structure is a grate.
17. The method of claim 16 , wherein the grate is periodic.
18. The method of claim 12 , wherein the structure is an array.
19. The method of claim 8 , wherein the structure is spaced apart from the compound semiconductor region by less than 2500 Angstroms.
20. A method of manufacturing a real-space charge transfer device comprising:
providing a substrate having planar active region disposed between a cathode and an anode, the planar active region having a length defined by a dimension between the cathode and the anode, and the active region being doped with an n-type dopant;
forming a conductive structure overlying the active region, wherein the conductive structure has a repetitive feature along the length of the active region, and is spaced apart from the active region by no more than 2500 Angstroms.