Room-temperature continuous-wave operation of GaN-based vertical-cavity surface-emitting lasers with n-type conducting AlInN/GaN distributed Bragg reflectors

Ikeyama, Kazuki; Kozuka, Yugo; Matsui, Kunihiko; Yoshida, Shigeo; Akagi, Takanobu; Akatsuka, Yasuto; Koide, Norikatsu; Takeuchi, Tetsuya; Kamiyama, Satoshi; Iwaya, Motoaki; Akasaki, Isamu

doi:10.7567/apex.9.102101

Cited by 81 publications

(56 citation statements)

References 30 publications

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“…Recently, technological progress in III-nitride based wide bandgap semiconductors has been greatly encouraged because of a continuous demand for energy saving, long lifetime, and environmentally friendly devices [1][2][3]. Since the bandgap of GaInN ternary alloys covers a broad spectral range, from visible to ultra-violet, these materials are suitable for optoelectronic devices such as light-emitting diodes (LEDs), laser diodes, solar-cells, and photo-detectors (PDs) [4][5][6][7]. III-nitride based semiconductors are typically grown on sapphire substrates by using metal-organic chemical vapor deposition (MOCVD) because homo-epitaxial substrates are still expensive due to a difficulty in mass production.…”

Section: Introductionmentioning

confidence: 99%

Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer

et al. 2019

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In this study, we compared the device performance of GaInN-based green LEDs grown on c-plane sapphire substrates with a conventional low temperature GaN buffer layer to those with a sputtered-AlN buffer layer. The light output power and leakage current characteristics were significantly improved by just replacing the buffer layer with a sputtered-AlN layer. To understand the origin of the improvement in performance, the electrical and optical properties were compared by means of electro-reflectance spectroscopy, I–V curves, electroluminescence spectra, L–I curves, and internal quantum efficiencies. From the analysis of the results, we concluded that the improvement is mainly due to the mitigation of strain and reduction of the piezoelectric field in the multiple quantum wells active region.

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Section: Introductionmentioning

confidence: 99%

Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer

et al. 2019

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“…Wide‐bandgap GaN‐based optoelectronic devices have attracted significant attention for a variety of commercial applications . One such device is the vertical‐cavity surface‐emitting laser (VCSEL) which has been heavily researched for their potential advantages over their edge‐emitting counterparts. VCSELs have a small active volume that emits normal to the device surface at low threshold currents.…”

Section: Introductionmentioning

confidence: 99%

“…Additionally, the low conductivity of p‐type GaN‐based materials and the difficulty in achieving conductive p‐type DBRs necessitates the use of an intracavity contact (i.e., current spreading layer) for injecting current into the active region. Although electrically injected CW lasing at room temperature (RT) has been demonstrated for GaN‐based VCSELs ; the output powers of these devices are limited to a few milliwatts by thermal roll‐over at high current densities. The self‐heating in these devices leads to an increase in non‐radiative carrier losses and a misalignment of the peak gain wavelength and the cavity resonance wavelength.…”

Section: Introductionmentioning

confidence: 99%

Techniques to reduce thermal resistance in flip‐chip GaN‐based VCSELs

Mishkat-Ul-Masabih

Leonard

Cohen

et al. 2017

Phys. Status Solidi A

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The finite element method was used to determine the thermal resistance of a flip‐chip‐bonded GaN‐based vertical‐cavity surface‐emitting laser (VCSEL) with substrate removal and dielectric distributed Bragg reflectors (DBRs). In this work, we investigate the effects of the DBR configuration, mask layer alignment tolerances, aperture diameters, and cladding layer thicknesses on the thermal properties of the flip‐chip design. The current flip‐chip design suffers from high thermal resistance (∼4600 K W−1). By reducing the mask layer alignment tolerances and increasing the cladding thickness, the thermal resistance values could be made comparable to devices reported in the literature that achieved CW operation at room temperature (∼3000 K W−1). Low thermal resistance designs are critical to achieve CW operation and mitigate the effects of thermal roll‐over in flip‐chip GaN‐based VCSELs.

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“…1,2 The progress of GaN-based VCSELs has been hampered by difficulties relating to growing low resistivity p-GaN, large lattice mismatch, and strong spontaneous and piezoelectric polarization fields in III-nitrides. Despite this, there have lately been several groups reporting on electrically injected GaN-based VCSELs [3][4][5][6][7][8][9][10][11][12] but further improvement is still needed in terms of lowering the threshold current density, increasing the output power and improving thermal stability.…”

Section: Introductionmentioning

confidence: 99%

“…Al 0.82 In 0.18 N/GaN is a lattice-matched alternative but also suffers from a small index contrast. Despite these challenges, crack-free and high reflectivity DBRs using both AlN/GaN 3,8,14,15 and AlInN/GaN 6,11,16,17 have been successfully grown and used as n-side DBRs in III-nitride VCSELs.…”

Section: Introductionmentioning

confidence: 99%

Electrically conductive ZnO/GaN distributed Bragg reflectors grown by hybrid plasma-assisted molecular beam epitaxy

et al. 2017

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III-nitride-based vertical-cavity surface-emitting lasers have so far used intracavity contacting schemes since electrically conductive distributed Bragg reflectors (DBRs) have been difficult to achieve. A promising material combination for conductive DBRs is ZnO/GaN due to the small conduction band offset and ease of n-type doping. In addition, this combination offers a small lattice mismatch and high refractive index contrast, which could yield a mirror with a broad stopband and a high peak reflectivity using less than 20 DBR-pairs. A crack-free ZnO/GaN DBR was grown by hybrid plasma-assisted molecular beam epitaxy. The ZnO layers were approximately 20 nm thick and had an electron concentration of 1×10 19 cm −3 , while the GaN layers were 80-110 nm thick with an electron concentration of 1.8×10 18 cm −3. In order to measure the resistance, mesa structures were formed by dry etching through the top 3 DBR-pairs and depositing non-annealed Al contacts on the GaN-layers at the top and next to the mesas. The measured specific series resistance was dominated by the lateral and contact contributions and gave an upper limit of ∼10 −3 Ω cm 2 for the vertical resistance. Simulations show that the ZnO electron concentration and the cancellation of piezoelectric and spontaneous polarization in strained ZnO have a large impact on the vertical resistance and that it could be orders of magnitudes lower than what was measured. This is the first report on electrically conductive ZnO/GaN DBRs and the upper limit of the resistance reported here is close to the lowest values reported for III-nitride-based DBRs.

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Room-temperature continuous-wave operation of GaN-based vertical-cavity surface-emitting lasers with n-type conducting AlInN/GaN distributed Bragg reflectors

Cited by 81 publications

References 30 publications

Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer

Enhanced Device Performance of GaInN-Based Green Light-Emitting Diode with Sputtered AlN Buffer Layer

Techniques to reduce thermal resistance in flip‐chip GaN‐based VCSELs

Electrically conductive ZnO/GaN distributed Bragg reflectors grown by hybrid plasma-assisted molecular beam epitaxy

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