Improvement of GaN-based laser diode facets by FIBpolishing

Mack, M.; Via, G. D.; Abare, A. C.; Hansen, M.; Kozodoy, P.; Keller, S.; Speck, James S.; Mishra, Umesh K.; Coldren, L.A.; DenBaars, Steven P.

doi:10.1049/el:19980886

Cited by 33 publications

(18 citation statements)

References 3 publications

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“…The achieved surface roughness and side wall roughness is comparable or better than etching results obtained with reactive ion etching (RIE) reported in the literature [11]. The superiority of FIB for the fabrication of GaN laser diode end facets has recently been illustrated by Mack et al [8]. FIBpost-processed GaN laser diodes showed a reduction in the threshold current, i.e., reduced optical losses in the end facet mirrors.…”

Section: Zhoo Ehorz P 7klv Uhvxow LV Yhu\ Surplvlqj Iru Xvh Ri )% Hwsupporting

confidence: 60%

“…Because of the difference in the cleavage plane between GaN (1100) and the commonly used sapphire substrate (1102) it is difficult to achieve flat cleaved end mirrors. The development of improved etching techniques is therefore essential to enhance the performance of GaN-based devices [6][7][8]. Furthermore, it will be necessary to find etching techniques which allow the fabrication of GaN on the nanometer scale for the development of novel device structures,, e.g., for integrating laser diodes with wavelength selective electro-absorbers [7].…”

Section: Introductionmentioning

confidence: 99%

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Focused Ion Beam Etching of GaN

Flierl

White

Kuball

et al. 1999

MRS Internet j. nitride semicond. res.

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We have investigated the use of focused ion beam (FIB) etching for the fabrication of GaN-based devices. Although work has shown that conventional reactive ion etching (RIE) is in most cases appropriate for the GaN device fabrication, the direct write facility of FIB etching -a well-established technique for optical mask repair and for IC failure analysis and repair -without the requirement for depositing an etch mask is invaluable. A gallium ion beam of about 20nm diameter was used to sputter GaN material. The etching rate depends linearly on the ion dose per area with a slope of 3.5x10

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Section: Zhoo Ehorz P 7klv Uhvxow LV Yhu\ Surplvlqj Iru Xvh Ri )% Hwsupporting

confidence: 60%

Section: Introductionmentioning

confidence: 99%

Focused Ion Beam Etching of GaN

Flierl

White

Kuball

et al. 1999

MRS Internet j. nitride semicond. res.

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show abstract

“…R is estimated to be approximately 0.053 for RIE etched facets. 22 Substituting Eqn. (2) into (1) and rearranging gives…”

Section: Resultsmentioning

confidence: 99%

Epitaxial Growth and Fabrication of Highly Strained Heterostructures

Denbaars¹

2000

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IB. yPONyOHINuMONITOHINUAULNOi REPORT NUMBERThe View», opinions and/or finding« contained in this report are those of the authors) and should not be construed as an official Department Of the Army position, policy and decision, unless so designated by other documentation. iSa. um i wyu i luwAVAiumu i v y i A minimApproved for public release; distribution unlimited. ABJSTHAIJI (ManmumM words EPITAXIAL GROWTH AND FABRICATIONOF HIGHLY STRAINED HETEROSTRUCTURES S.P. DenBaars (P.I.) Department of Electrical and Computer Engineering and MaterialsUniversity of California, Santa Barbara, CA 93106 ABSTRACTRoom temperature (RT) pulsed operation of blue nitride based multi-quantum well (MQW) laser diodes grown on c-plane sapphire substrates were achieved. Emission wavelengths as long as 425nm were obtained. Atmospheric pressure MOCVD was used to grow the active region of the device which consisted of a 10 pair Ino.21Gao.79N (2.5nm)/Ino.o7Gao.93N (5nm) InGaN MQW. The threshold current density was reduced by a factor of 2 from 10 kA/cm 2 for laser diodes grown on sapphire substrates to 4.8 kA/cm for laser diodes grown on LEO GaN on sapphire. These results show that a reduction in nonradiative recombination from a reduced dislocation density leads to a higher internal quantum efficiency. The researchers would like to thank the generous support and guidance of Dr. John Zavada. Further research on lateral epitaxial overgrowth (LEO) is needed to extend the wavelength to 490nm which is required for numerous bio-chemical sensing applications.

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“…To date, several methods have been employed to fabricate facets for GaN-based near-UV lasers including cleaving, 29,30 milling with focused ion beams (FIB), 31,32 plasma etching, [33][34][35] chemically assisted ion beam etching, 36,37 and two-step processes combining plasma etching or photoenhanced electrochemical etching with wet chemical etching. [38][39][40][41][42] Of these methods, cleaving has produced the smoothest facet surfaces with root mean square (RMS) roughness values on the order of 1 nm for GaN-based laser diodes (LDs) grown on SiC.…”

Section: Processes For High Quality Etched Facetsmentioning

confidence: 99%

“…Careful manipulation of plasma-etching parameters have led to GaN-based laser facets with RMS roughness values on the order of 20 nm 5 and facet angles ranging from 5° to 1° from vertical. 31,33 Further improvements to plasma-etched facets have been achieved with subsequent wet chemical etching using KOH-based solutions that reveal particular crystallographic planes. 39 In the work reported here, we advance this two-step method by optimizing both inductivelycoupled plasma (ICP) etching and wet-etching parameters and demonstrating applicability to Al x Ga 1-x N-based deep-UV laser structures comprising a wide compositional range.…”

Section: Processes For High Quality Etched Facetsmentioning

confidence: 99%

Final LDRD report : science-based solutions to achieve high-performance deep-UV laser diodes.

Armstrong¹,

Miller²,

Crawford³

et al. 2011

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We present the results of a three year LDRD project that has focused on overcoming major materials roadblocks to achieving AlGaN-based deep-UV laser diodes. We describe our growth approach to achieving AlGaN templates with greater than ten times reduction of threading dislocations which resulted in greater than seven times enhancement of AlGaN quantum well photoluminescence and 15 times increase in electroluminescence from LED test structures. We describe the application of deep-level optical spectroscopy to AlGaN epilayers to quantify deep level energies and densities and further correlate defect properties with AlGaN luminescence efficiency. We further review our development of p-type short period superlattice structures as an approach to mitigate the high acceptor activation energies in AlGaN alloys. Finally, we describe our laser diode fabrication process, highlighting the development of highly vertical and smooth etched laser facets, as well as characterization of resulting laser heterostructures. 4 ACKNOWLEDGMENTSThe authors gratefully acknowledge Blythe Clark, and Qiming Li for providing assistance in materials characterization. We appreciate the support of managers Dan Barton (project manager), Robert Biefeld, and Jerry Simmons throughout this work.5

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Improvement of GaN-based laser diode facets by FIBpolishing

Cited by 33 publications

References 3 publications

Focused Ion Beam Etching of GaN

Focused Ion Beam Etching of GaN

Epitaxial Growth and Fabrication of Highly Strained Heterostructures

Final LDRD report : science-based solutions to achieve high-performance deep-UV laser diodes.

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