| Summary: | 碩士 === 國立清華大學 === 電子工程研究所 === 92 === Photoelectrochemical etching (PEC) is a photon assisted wet etching. Low damage and high etching rate makes it a good method for etching n-type GaN. By using K2S2O8 as the oxidizing agent, the technique of electrodless photoeletro-
chemical etching (ELPEC) was built to improve the problem of lateral distribution of etching depth in conventional PEC etching. Finally, the chopped photon assisted photoelectrochemical etching makes it possible to produce a broad area smooth etching surface and the root-mean square roughness is 0.37nm. According to this achievement, we propose that the chopped photon assisted wet etching can be used to create smooth etching surface for nano-dot deposition and even the nano-scale structure etching technique.
To fabricate a light emitting diode (LED), etch through the p-i-n structure is necessary and the p-type etching is a main problem for PEC etching that we have to overcome. By using the chopped photon assisted wet etching (CPAWE) method, we have the ability of etching p-type GaN and then create the simplest LED device successfully with the p-i-n structure sample.
Finally, to achieve our goal to complete the nano scale etching technique, we must establish a nano-lithography technique to create the nano scale etching mask. E-beam lithography is adopted to fabricate our nano structure. Both gold and PMMA were used as etching mask in this experiment. A near 100nm straight line is produced by chopped photon assisted wet etching at diffusion limit etching condition. From this research, we prove the property of nano-scale etching with CPAWE and it can be used to fabricate a nano scale light emission device.
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