Direct bandgap substrates and methods of making and using

• US 9,666,600 B2
• Filed: 01/28/2016
• Issued: 05/30/2017
• Est. Priority Date: 08/16/2007
• Status: Active Grant

• Current Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Original Assignee: Trustees Of Columbia University In The City Of New York (Columbia University)
• Inventors: Kymissis, Ioannis, Lee, Vincent Wing-Ho
• Primary Examiner(s): SINGAL, ANKUSH K
• Application Number:
  US15/009,284
• Publication Number:
  US 20160225793A1
• Time in Patent Office: 488 Days
• CPC Class Codes: H01L 27/1218 with a particular composition or structure of the substrate
• CPC Class Codes: H01L 27/1222 with a particular composition, shape or crystalline structure of the active layer
• CPC Class Codes: H01L 27/124 with a particular composition, shape or layout of the wiring layers specially adapted to the circuit arrangement, e.g. scanning lines in LCD pixel circuits wiring structures per se H01L23/52
• CPC Class Codes: H01L 27/1285 using control of the annealing or irradiation parameters, e.g. using different scanning direction or intensity for different transistors
• CPC Class Codes: H01L 27/1446 in a repetitive configuration
• CPC Class Codes: H01L 27/153 in a repetitive configuration, e.g. LED bars
• CPC Class Codes: H01L 33/005 Processes
• CPC Class Codes: H01L 33/26 Materials of the light emitting region
• CPC Class Codes: H01L 33/502 Wavelength conversion materials
• CPC Class Codes: H04N 9/315 Modulator illumination systems general applications of lighting devices F21V; general optical systems G02B; lamp houses for projectors not peculiar to the presence of an electronic spatial light modulator G03B21/20

Abstract

An indirect bandgap thin film semiconductor circuit can be combined with a compound semiconductor LED such as to provide an active matrix LED array that can have high luminous capabilities such as for a light projector application. In another example, a highly efficient optical detector is achievable through the combination of indirect and direct bandgap semiconductors. Applications can include display technologies, light detection, MEMS, chemical sensors, or piezoelectric systems. An LED array can provide structured illumination, such as for a light and pattern source for projection displays, such as without requiring spatial light modulation (SLM). An example can combine light from separate monolithic light projector chips, such as providing different component colors. An example can provide full color from a single monolithic light projector chip, such as including selectively deposited phosphors, such as to contribute individual component colors to an overall color of a pixel.

Claims

1. A method comprising:

providing an inorganic substrate with a substantially direct bandgap for light emission or absorption, including forming a metal contact to the substrate;

forming an insulating layer on a first side of the substrate;

forming a direct bandgap semiconductor layer on the insulating layer;

selectively heating and crystallizing an active region of the direct bandgap semiconductor layer formed on the insulating layer;

forming an electrical contact to the crystallized active region in the direct bandgap semiconductor layer; and

forming an electrical contact to the substrate.

2. The method of claim 1, wherein the direct bandgap semiconductor layer is selected from the group consisting of ZnO, alloys of ZnO, and organic material.

3. The method of claim 1, comprising:

forming a thin film semiconductor transistor in the active region;

wherein forming an electrical contact to the crystallized active region in the direct bandgap semiconductor layer comprises forming electrodes contacting the thin film semiconductor transistor;

forming an insulating layer over the thin film semiconductor transistor; and

forming vias in the insulating layer over the thin film semiconductor transistor.

4. The method of claim 1, wherein providing the substrate comprises providing a compound semiconductor substrate comprising at least one of GaAs, AlGaAs, AlGaP, AlGaInP, GaAsP, GaP, GaN, AlGaN, InGaN, SiC, ZnSe, AlN, AlGaN, AlGaInN, C, InAlP, InSb, InAlSb, or HgCdTe.

5. The method of claim 1, comprising:

forming a gate insulator on the selectively heated and crystallized active region of the silicon layer;

forming a gate on the gate insulator; and

forming an insulating layer over the active region, the insulating layer comprising at least one of parylene, polyimide, SiOx, SiNx, SiNOx, DLC, HfO, Al₂O₃, TaOx, RuOx, metal oxide, nitride, fluoride, chloride, polymer, or fluorocarbon.

6. An apparatus comprising:

an inorganic light emitting or absorbing device formed from an inorganic substrate providing a substantially direct bandgap for light emission or absorption, including a metal contact formed on the substrate;

an insulating layer on a first side of the substrate;

a direct bandgap semiconductor layer on the insulating layer;

a thin film semiconductor circuit, in the direct bandgap semiconductor layer, the semiconductor circuit comprising a selectively heated and crystallized polycrystalline grain semiconductor active region; and

an electrical connection, through the insulating layer, electrically connecting the inorganic light emitting or absorbing device with the thin film semiconductor circuit.

7. The apparatus of claim 6, wherein the direct bandgap semiconductor layer is selected from the group consisting of ZnO, alloys of ZnO, and organic material.

8. The apparatus of claim 6, wherein the inorganic light emitting or absorbing device comprises an inorganic light emitting diode (LED) formed in the substrate, the LED comprising:

an n-type cathode region of the substrate;

a p-type anode region of the substrate; and

wherein the apparatus comprises a plurality of the LEDs arranged in an active matrix array.

9. The apparatus of claim 6, comprising pixels, an individual pixel including a plurality of sub-pixels, an individual sub-pixel including a phosphor that is configured to receive light from an inorganic LED in the substrate and to pass a specified color of light in response to the received light, and wherein the individual sub-pixels individually contribute respective colors to an overall color of light provided by the individual pixel.

10. The apparatus of claim 6, comprising a light projector or a direct-view display comprising pixels, and wherein the pixels are monolithically integrated with the substrate.

11. The apparatus of claim 6, comprising a light projector comprising pixels, and wherein the pixels are configured to provide a directly addressed monolithic LED array light projection source configured to provide both a light source and a light modulator in the same component.