Photo-enhanced chemical wet etching of GaN

Ko, Chih-Hsin; Su, Yan–Kuin; Chang, Shoou‐Jinn; Lan, Wen−How; Webb, J. B.; Tu, Ming-Lung; Cherng, Ya-Tung

doi:10.1016/s0921-5107(02)00323-9

Cited by 39 publications

(28 citation statements)

References 13 publications

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“…Figure 6 shows the SEM images of GaN etch morphology using PEC wet etching of samples with (a) high and (b) low dislocation density [15] . According to ref.…”

Section: Resultsmentioning

confidence: 99%

Roughening surface morphology on free-standing GaN membrane with laser lift-off technique

et al. 2007

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COMMUNICATION TECHNOLOGY ed by sapphire. An ultraviolet (UV) laser lift-off (LLO) technique was presented to form a roughened surface morphology on GaN membrane grown by metalorganic chemical vapor deposition (MOCVD). The etched surface showed cone-like structures on a free-standing GaN membrane. Based on the scanning electron microscopy (SEM) and atom force microscopy (AFM) measurements, the etching mechanism was proposed, which was related to the different decomposition depth caused by the dislocations in the GaN membrane. The etching efficiency and morphology of GaN by the LLO technique and the photoelectrochemical (PEC) wet etching technique was compared and analyzed. This roughed cone-like surface morphology by LLO can enhance the external efficiency of vertical structure n-side-up GaN-based light-emitting diodes (LEDs) simultaneously while being released of the performance constrains imped laser lift-off, roughening, GaN, chemical wet etchThere are numerous applications for GaN-based optoelectronic and electronics devices. High efficiency GaN-based light-emitting diodes (LEDs) are one of the most important applications, which can be used in many fields including full-color displays, green traffic lights, and flat-panel room lighting to replace incandescent and fluorescent fixtures [1,2] . However, the total light output from these LEDs is still rather low. The internal quantum efficiency has already reached about 90% by improving the crystal quality and epitaxial layer structure. Much improvement can be achieved in the external quantum efficiency (η ext ), which is primarily limited by the total internal reflection of the light generated from the active region at the interface of the semiconductor and air. Texturing the top surface of a LED is the most well known method to improve the light extraction among many methods [3][4][5][6] . A dry etching method was employed on top of the LED using a mask for texture patterning [7,8] . In this case, serious damage can be induced due to the formation of surface defects such as vacancies, impurities and residuals by the dry etching process. Thus, many researchers have attempted to replace the dry etching process with a wet etching process for texturing the surface. Photoelectrochemical (PEC) wet etching has been demonstrated to provide a broad and smooth etched surface with a vertical anisotropic profile [9,10] . However, three disadvantages of PEC etching encountered in device fabrication are the lateral potential gradient on the GaN membrane, the narrow region of operation for a smooth etched surface and the incapability of etching p-GaN directly. The lateral potential gradient was present along the distance from the conducting electrode to the GaN membrane; a non-uniform depth of etching then occurred along the potential gradient.

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“…Figure 6 shows the SEM images of GaN etch morphology using PEC wet etching of samples with (a) high and (b) low dislocation density [15] . According to ref.…”

Section: Resultsmentioning

confidence: 99%

Roughening surface morphology on free-standing GaN membrane with laser lift-off technique

et al. 2007

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“…Whiskerlike shapes were observed for pH = 0.4, 2.7 and 6.2 electrolytes, but were not observed for pH = 11.9 and 13.6 electrolytes. Hexagonal-shaped columns were observed for pH = 11.9 and 13.6 [7]. The pH dependence of the chemical composition of the surface is shown in Fig.…”

Section: Energy [Ev]mentioning

confidence: 88%

Investigation of surface morphology of n‐type GaN after photoelectrochemical reaction in various solutions for H₂ gas generation

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et al. 2007

Phys. Status Solidi (c)

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“…Similar results were recorded with the GaN electrode in KBr and KI solutions, where the slope changes remained less than 10 mV/decade. The drift of the GaN electrode was the largest in the KNO 3 solutions at an average of 1.57 mV/day. The average GaN electrode drift in KBr and KI solutions is 0.89 mV/day and 0.83 mV/day, respectively.…”

Section: Electrode Driftmentioning

confidence: 99%

“…The observed pH sensitivity of the GaN and In 0.2 Ga 0.8 N electrodes in the pH range from 1.3 to 12.8 is attributed to progressive desorption of hydroxide anions initially adsorbed at positive adsorption sites on the electrode surface. The drift of the GaN electrode potential reached an average value of 1.57 mV/day in KNO 3 solutions, but could not be evaluated for the In 0.2 Ga 0.8 N electrode because of a large change in electrode slope over time. The cyclic voltammetry experiments helped identify the stability range of the GaN electrode.…”

Section: Surface Studiesmentioning

confidence: 99%

“…Although, in theory, many semiconductor materials can be employed as ISEs, gallium nitride (GaN) and indium gallium nitride (In x Ga 1Àx N) offer significant advantages over other semiconductors. Their excellent mechanical/ thermal/chemical stability [2 -4], their resistance to corrosion [3,4], their low toxicity if dissolved, and the presence of a polarization-induced surface charge [5] make these semiconductors prime candidates for a variety of sensor applications, particularly at high temperatures and in harsh environments [5].…”

Section: Introductionmentioning

confidence: 99%

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Evaluation of GaN and In_0.2Ga_0.8N Semiconductors as Potentiometric Anion Selective Electrodes

et al. 2007

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Photo-enhanced chemical wet etching of GaN

Cited by 39 publications

References 13 publications

Roughening surface morphology on free-standing GaN membrane with laser lift-off technique

Roughening surface morphology on free-standing GaN membrane with laser lift-off technique

Investigation of surface morphology of n‐type GaN after photoelectrochemical reaction in various solutions for H₂ gas generation

Evaluation of GaN and In_0.2Ga_0.8N Semiconductors as Potentiometric Anion Selective Electrodes

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Photo-enhanced chemical wet etching of GaN

Cited by 39 publications

References 13 publications

Roughening surface morphology on free-standing GaN membrane with laser lift-off technique

Roughening surface morphology on free-standing GaN membrane with laser lift-off technique

Investigation of surface morphology of n‐type GaN after photoelectrochemical reaction in various solutions for H2 gas generation

Evaluation of GaN and In0.2Ga0.8N Semiconductors as Potentiometric Anion Selective Electrodes

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Investigation of surface morphology of n‐type GaN after photoelectrochemical reaction in various solutions for H₂ gas generation

Evaluation of GaN and In_0.2Ga_0.8N Semiconductors as Potentiometric Anion Selective Electrodes