Metal-oxide-semiconductor field-effect phototransistors based on single crystalline semiconductor thin films

Patent metadata

Field	Value
Publication number	US-9653640-B2
Application number	US-201514879241-A
Country	US
Kind code	B2
Filing date	Oct 9, 2015
Priority date	Oct 9, 2015
Publication date	May 16, 2017
Grant date	May 16, 2017

Abstract

MOSFET phototransistors, methods of operating the MOSFET phototransistors and methods of making the MOSFET phototransistors are provided. The phototransistors have a buried electrode configuration, which makes it possible to irradiate the entire surface areas of the radiation-receiving surfaces of the phototransistors.

First claim

What is claimed is:

1. A metal-oxide-semiconductor field-effect phototransistor comprising:
a substrate;
a single-crystalline semiconductor film comprising: a radiation-receiving surface; an opposing, substrate-facing surface; a source region; a drain region; and a channel region;
a gate stack comprising a gate dielectric and a gate electrode, wherein the gate stack is disposed on the substrate-facing surface of the single-crystalline semiconductor film, between the channel region of the single-crystalline semiconductor film and the substrate;
a source electrode disposed on the substrate-facing surface of the single-crystalline semiconductor film, between the source region of the single-crystalline semiconductor film and the substrate;
a drain electrode disposed on the substrate-facing surface of the single-crystalline semiconductor film, between the drain region of the single-crystalline semiconductor film and the substrate; and
an antireflective coating on the radiation-receiving surface of the single-crystalline semiconductor film.

2. The phototransistor of claim 1 , wherein at least one of the source electrode, gate electrode and drain electrode is configured to reflect radiation that traverses the single-crystalline semiconductor film back into the single-crystalline semiconductor film.

3. The phototransistor of claim 2 , wherein each of the source electrode, gate electrode and drain electrode are configured to reflect radiation that traverses the single-crystalline semiconductor film back into the single-crystalline semiconductor film.

4. The phototransistor of claim 1 , wherein the substrate is a polymeric substrate and the phototransistor is mechanically flexible.

5. The phototransistor of claim 1 , wherein a surface of the substrate in contact with the source electrode, gate electrode and drain electrode comprises an adhesive coating.

6. The phototransistor of claim 1 , wherein the antireflective coating and the adhesive coating both comprise an epoxy polymer.

7. The phototransistor of claim 1 , wherein the antireflective coating defines a pattern configured to increase the incident radiation collection efficiency of the phototransistor, relative to the incident radiation collection efficiency provided by an unpatterned antireflective coating.

8. The phototransistor of claim 7 , wherein the substrate is a mechanically flexible, polymeric substrate.

9. The phototransistor of claim 8 , wherein a surface of the substrate in contact with the source electrode, gate electrode and drain electrode comprises an adhesive coating.

10. The phototransistor of claim 1 , wherein the single-crystalline semiconductor film is a single-crystalline Group IV semiconductor film.

11. The phototransistor of claim 10 , wherein the single-crystalline semiconductor film is a single-crystalline silicon film.

12. The phototransistor of claim 1 , wherein the single-crystalline semiconductor film has a thickness of no greater than 400 nm.

13. The phototransistor of claim 1 , wherein the source electrode, gate electrode, and drain electrode comprise aluminum or silver.

14. A method of controlling the drain current in a metal-oxide-semiconductor field-effect phototransistor comprising:
a substrate;
a single-crystalline semiconductor film comprising: a radiation-receiving surface; an opposing, substrate-facing surface; a source region; a drain region; and a channel region;
a gate stack comprising a gate dielectric and a gate electrode, wherein the gate stack is disposed on the substrate-facing surface of the single-crystalline semiconductor film, between the channel region of the single-crystalline semiconductor film and the substrate;
a source electrode disposed on the substrate-facing surface of the single-crystalline semiconductor film, between the source region of the single-crystalline semiconductor film and the substrate;
a drain electrode disposed on the substrate-facing surface of the single-crystalline semiconductor film, between the drain region of the single-crystalline semiconductor film and the substrate; and
an antireflective coating on the radiation-receiving surface of the single-crystalline semiconductor film;
the method comprising:
applying a gate voltage to the gate electrode; and
irradiating the radiation-receiving surface of the single-crystalline semiconductor film with incident radiation, whereby charge carriers are created in the single-crystalline semiconductor layer, which modulates the gate voltage and the drain current in the phototransistor.

15. The method of claim 14 , wherein the photocurrent to dark current ratio of the phototransistor is at least 10 4 .

16. The method of claim 14 , wherein the phototransistor has a responsivity of at least 40 A/W.

17. A method of fabricating a metal-oxide-semiconductor field-effect phototransistor, the method comprising:
forming a source region, a drain region, and a channel region in a single-crystalline semiconductor film that is attached to a sacrificial substrate, the single-crystalline semiconductor substrate comprising a first surface and a second surface facing opposite the first surface;
releasing the single-crystalline semiconductor film from the sacrificial substrate;
forming a source electrode over the source region on the first surface of the single-crystalline semiconductor film; forming a drain electrode over the drain region on the first surface of the single-crystalline semiconductor film; and forming a gate stack comprising a gate dielectric and a gate electrode over the channel region on the first surface of the single-crystalline semiconductor film;
attaching the released single-crystalline semiconductor film onto a support substrate, with the source electrode, gate stack, and drain electrode facing the support substrate, such that second surface of the single-crystalline semiconductor film is facing away from the support substrate; and
applying an antireflective coating over the second surface of the single-crystalline semiconductor film.

18. The method of claim 17 , wherein the support substrate is a polymeric substrate and the phototransistor is mechanically flexible.

19. The method of claim 17 , wherein the antireflective coating defines a pattern configured to increase the incident radiation collection efficiency of the phototransistor, relative to the incident radiation collection efficiency provided by an unpatterned antireflective coating.

Assignees

• Wisconsin Alumni Res Found

Inventors

• Ma Zhenqiang
• Seo Jung-Hun

Classifications

• H01L31/03921

  Electricity · mapped topic

• H01L31/022408

  Electricity · mapped topic

• H01L31/1136 Primary

  Electricity · mapped topic

• H01L31/1013

  Electricity · mapped topic

• H01L31/02327

  Electricity · mapped topic