Metal/semiconductor/metal (MSM) back-to-back Schottky diode

1. A method for forming a metal/semiconductor/metal(MSM) back-to-back Schottky diode from a silicon (Si) semiconductor, the method comprising:

depositing an amorphous Si (a-Si) semiconductor layer between a bottom electrode and a top electrode with a DC sputtering process as follows:

using a Si target;

sputtering with a power in the range of about 100 to 300 watts (W);

heating a substrate to a temperature of about 20° to 200° C.;

creating a deposition pressure in the range of about 7.0 to 9 mtorr;

using an atmosphere of Ar;

depositing for a duration in the range of about 7 to 150 minutes; and,

forming a-Si;

forming a MSM diode having a threshold voltage, a breakdown voltage, and an on/off current ratio; and,

modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode in response to controlling a thickness of the Si semiconductor layer.

2. The method of claim 1 further comprising:

following the formation of the a-Si, annealing at a temperature greater than 550° C.; and,

forming polySi.

3. The method of claim 1 wherein modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode includes decreasing the threshold voltage, increasing the breakdown voltage, and decreasing the on/off current ratio in response to increasing the DC sputtering power.

4. The method of claim 1 wherein modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode includes decreasing the threshold voltage, increasing the breakdown voltage, and decreasing the on/off current ratio in response to increasing the substrate temperature.

5. The method of claim 1 wherein forming the a-Si semiconductor with the DC sputtering process includes using an oxygen partial pressure in the range of 0 to 5%; and, wherein modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode includes increasing the threshold voltage and increasing the breakdown voltage in response to increasing the oxygen partial pressure.

6. The method of claim 5 wherein depositing the a-Si semiconductor layer includes forming an a-Si semiconductor layer having a first thickness; and,

wherein modifying the on/off current ratio of the MSM diode in response to increasing the oxygen partial pressure includes:

decreasing the on/off current ratio when the Si thickness is less than the first thickness; and,

decreasing the on/off current ratio when the Si thickness is greater than the first thickness.

7. The method of claim 1 wherein modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode includes increasing the threshold voltage and increasing the breakdown voltage in response to increasing the Si thickness.

8. The method of claim 7 wherein depositing the a-Si semiconductor layer includes forming an a-Si semiconductor layer having a first thickness; and,

wherein modifying the on/off current ratio of the MSM diode includes:

increasing both the on and off currents in response to decreasing the Si thickness below the first thickness; and,

decreasing both the on and off currents in response to increasing the Si thickness above the first thickness.

9. The method of claim 1 further comprising:

doping the a-Si semiconductor layer with a Group V donor material; and,

wherein modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode includes decreasing the threshold voltage and increasing the breakdown voltage in response to increasing the doping the Si semiconductor layer.

10. The method of claim 9 wherein depositing the a-Si semiconductor layer includes forming an a-Si semiconductor layer having a first thickness; and,

wherein modifying the on/off current ratio of the MSM diode in response to doping the Si semiconductor layer includes:

decreasing the on/off current ratio when the Si thickness is less than the first thickness; and,

decreasing the on/off current ratio when the Si thickness is greater than the first thickness.

11. The method of claim 9 wherein doping the a-Si semiconductor layer includes:

implanting As with an energy of about 30 keV and a dose of about 1×10 12 ; and,

annealing at a temperature of about 500° C. for about 10 minutes.

12. The method of claim 2 wherein forming polySi includes forming polySi having a thickness in the range of about 600 to 1200 nanometers (nm);

the method further comprising:

doping the polySi as follows:

implanting B with an energy of about 200 keV and a dose of about 1×10 13 ;

implanting As with an energy of about 30 keV and a dose of about 2×10 15 ; and,

annealing at a temperature in the range of about 700° to 900° C. for about 30 to 90 minutes; and

wherein modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode includes decreasing the threshold voltage and increasing the breakdown voltage in response to increasing the doping the polySi semiconductor layer.

13. A method for forming a metal/semiconductor/metal (MSM) back-to-back Schottky diode from a silicon (Si) semiconductor, the method comprising:

depositing a Si semiconductor layer having first thickness between a bottom electrode and a top electrode;

forming a MSM diode having a threshold voltage, a breakdown voltage, and an on/off current ratio;

increasing the threshold voltage and the breakdown voltage of the MSM diode in response to increasing a first thickness of the Si semiconductor layer;

increasing both on and off currents of the MSN diode in response to decreasing the Si thickness below the first thickness; and,

decreasing both the on and off currents in response to increasing the Si thickness above the first thickness.

14. A method for forming a metal/semiconductor/metal (MSM) back-to-back Schottky diode from a silicon (Si) semiconductor, the method comprising:

depositing a Si semiconductor layer between a bottom electrode and a top electrode with a CVD process as follows:

flowing silane at a rate in the range of about 40 to 200 standard cubic centimeters (sccm);

heating the substrate to a temperature in the range of about 500 to 600° C.;

creating a deposition pressure in the range of about 150 to 250 milliTorr (mtorr); and,

depositing for a duration in the range of about 10 minutes to 6 hours;

forming a MSM diode having a threshold voltage, a breakdown voltage, and an on/off current ratio; and,

modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode in response to controlling a thickness of the Si semiconductor layer.

15. A method for forming a metal/semiconductor/metal (MSM) back-to-back Schottky diode from a silicon (Si) semiconductor, the method comprising:

depositing a Si semiconductor layer selected from a group consisting of amorphous Si (a-Si) and polycrystalline Si (polySi) between a bottom electrode and a top electrode;

doping the Si semiconductor layer with a Group V donor material;

forming a MSM diode having a threshold voltage, a breakdown voltage, and an on/off current ratio;

modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode in response to controlling a thickness of the Si semiconductor layer; and,

wherein modifying the threshold voltage, the breakdown voltage, and the on/off current ratio of the MSM diode includes decreasing the threshold voltage and increasing the breakdown voltage in response to increasing the doping the Si semiconductor layer.