Control of photoelectrochemical (PEC) etching by modification of the local electrochemical potential of the semiconductor structure relative to the electrolyte

• US 20060110926A1
• Filed: 10/31/2005
• Published: 05/25/2006
• Est. Priority Date: 11/02/2004
• Status: Active Grant

• Current Assignee: Regents of the University of California (University of California)
• Original Assignee: Regents of the University of California (University of California)
• Inventors: Sharma, Rajat, Nakamura, Shuji, Hu, Evelyn L., Haberer, Elaine D.
• Granted Patent: US 7,550,395 B2
• Time in Patent Office: Days
• US Class Current: 438/708
• CPC Class Codes: B82Y 20/00 Nanooptics, e.g. quantum optics or photonic crystals
• CPC Class Codes: H01L 21/30635 of AIIIBV compounds
• CPC Class Codes: H01L 33/10 with a light reflecting structure, e.g. semiconductor Bragg reflector
• CPC Class Codes: H01S 2304/12 Pendeo epitaxial lateral overgrowth [ELOG], e.g. for growing GaN based blue laser diodes
• CPC Class Codes: H01S 5/1075 Disk lasers with special modes, e.g. whispering gallery lasers
• CPC Class Codes: H01S 5/18316 Airgap confined
• CPC Class Codes: H01S 5/2081 using special etching techniques
• CPC Class Codes: H01S 5/34333 with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser

Abstract

A method for locally controlling an electrical potential of a semiconductor structure or device, and hence locally controlling lateral and/or vertical photoelectrochemical (PEC) etch rates, by appropriate placement of electrically resistive layers or layers that impede electron flow within the semiconductor structure, and/or by positioning a cathode in contact with specific layers of the semiconductor structure during PEC etching.

Claims

1. A method for fabricating a III-nitride semiconductor structure comprising strategically modifying a local electrochemical potential of the semiconductor structure relative to an electrolyte to achieve a highly selective photo-induced etch.

2. The method of claim 1, wherein the strategically modifying step comprises performing a suitable placement of electrically resistive (unintentionally-doped, doped or alloyed) or electron-blocking layers in the semiconductor structure.

3. The method of claim 1, wherein the strategically modifying step comprising selectively placing a cathode for photoelectrochemical (PEC) etching, wherein the cathode acts as a channel for controlled collection of photo-generated electrons from semiconductor layers with which it is in contact.

4. The method of claim 1, wherein the strategically modifying step comprising using a suitable light source during photoelectrochemical (PEC) etching, which enables photo-generation of electrons and holes in layers with bandgap energies lower than the energy of incident light.

5. The method of claim 1, wherein the strategically modifying step comprising using a suitable electrolyte solution during photoelectrochemical (PEC) etching, wherein the electrolyte'"'"'s concentration and type determines etch rate and etch selectivity.

6. High-quality nitride-based microdisk resonators fabricated using the method of claim 1.

7. High-quality vertically oriented nitride-based air-gap distributed Bragg reflector (DBR) structures fabricated using the method of claim 1.

8. A method for locally controlling an electrical potential of a semiconductor structure or device, and hence locally controlling lateral and/or vertical photoelectrochemical (PEC) etch rates, by appropriate placement of electrically resistive layers or layers that impede electron flow within the semiconductor structure, and/or by positioning a cathode in contact with specific layers of the semiconductor structure during PEC etching.