Demonstration of Blue and Green GaN-Based Vertical-Cavity Surface-Emitting Lasers by Current Injection at Room Temperature

Kasahara, Daiji; Morita, Daisuke; Kosugi, Takao; Nakagawa, Kyosuke; Kawamata, Jun; Higuchi, Yu; Matsumura, Hiroaki; Mukai, Takashi

doi:10.1143/apex.4.072103

Cited by 177 publications

(138 citation statements)

References 17 publications

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“…For the gain region of the laser we consider a 3 nm thick single strained In 0.1 Ga 0.9 N QW, surrounded by 6 nm GaN barriers, the typical lengths and composition of (In,Ga)N-based vertical cavity surface emitting lasers (VCSELs) [52][53][54][55]. The bulk InN and GaN parameters are obtained from Ref.…”

Section: Quantum Well Electronic Structurementioning

confidence: 99%

Wurtzite spin lasers

Faria

Chen

et al. 2017

Phys. Rev. B

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Semiconductor lasers are strongly altered by adding spin-polarized carriers. Such spin lasers could overcome many limitations of their conventional (spin-unpolarized) counterparts. While the vast majority of experiments in spin lasers employed zinc-blende semiconductors, the room temperature electrical manipulation was first emonstrated in wurtzite GaN-based lasers. However, the underlying theoretical description of wurtzite spin lasers is still missing. To address this situation, focusing on (In,Ga)N-based wurtzite quantum wells, we develop a theoretical framework in which the calculated microscopic spin-dependent gain is combined with a simple rate equation model. A small spin-orbit coupling in these wurtzites supports simultaneous spin polarizations of electrons and holes, providing unexplored opportunities to control spin lasers. For example, the gain asymmetry, as one of the key figures of merit related to spin amplification, can change the sign by simply increasing the carrier density. The lasing threshold reduction has a nonmonotonic depenedence on electron spin polarization, even for a nonvanishing hole spin polarization.

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Section: Quantum Well Electronic Structurementioning

confidence: 99%

Wurtzite spin lasers

Faria

Chen

et al. 2017

Phys. Rev. B

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“…Publications from a few groups followed, and since the first demonstrations there have been a lot of progress in the field of electrically injected III-nitride based VCSELs, both in terms of new technological solutions as well as performance characteristics. 31 To date there are seven groups in the world who have demonstrated lasing under electrical injection [27][28][29][30][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47] , and the different approaches and structures are summarized in Table 1. The performance characteristics of published devices, in terms of output power and threshold current density, are plotted in Fig.…”

Section: State-of-the-artmentioning

confidence: 99%

“…In the early works on electrically injected GaN-based VCSELs, the main focus on apertures was to obtain a good lateral current confinement without paying too much attention to the impact on optical properties 27,28,30,32,33,40,44,45 . The method applied was to create an aperture by depositing an electrically non-conductive layer (often SiO2 or SixNy) on the p-GaN on top of the mesa and then fabricating a hole in the center onto which a transparent conductive layer (ITO) was deposited to pass the current through.…”

Section: Guiding and Antiguiding Effectsmentioning

confidence: 99%

Progress and challenges in electrically pumped GaN-based VCSELs

et al. 2016

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The Vertical-Cavity Surface-Emitting Laser (VCSEL) is an established optical source in short-distance optical communication links, computer mice and tailored infrared power heating systems. Its low power consumption, easy integration into two-dimensional arrays, and low-cost manufacturing also make this type of semiconductor laser suitable for application in areas such as high-resolution printing, medical applications, and general lighting. However, these applications require emission wavelengths in the blue-UV instead of the established infrared regime, which can be achieved by using GaN-based instead of GaAs-based materials. The development of GaN-based VCSELs is challenging, but during recent years several groups have managed to demonstrate electrically pumped GaN-based VCSELs with close to 1 mW of optical output power and threshold current densities between 3-16 kA/cm 2 . The performance is limited by challenges such as achieving high-reflectivity mirrors, vertical and lateral carrier confinement, efficient lateral current spreading, accurate cavity length control and lateral optical mode confinement. This paper summarizes different strategies to solve these issues in electrically pumped GaN-VCSELs together with state-of-the-art results. We will highlight our work on combined transverse current and optical mode confinement, where we show that many structures used for current confinement result in unintentionally optically anti-guided resonators. Such resonators can have a very high optical loss, which easily doubles the threshold gain for lasing. We will also present an alternative to the use of distributed Bragg reflectors as high-reflectivity mirrors, namely TiO2/air high contrast gratings (HCGs). Fabricated HCGs of this type show a high reflectivity (>95%) over a 25 nm wavelength span.

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“…III-nitride vertical-cavity surface-emitting lasers can be divided into two classes: dual dielectric distributed Bragg reflector (DBR) VCSELs, [23][24][25][26][27][28][29][30][31][32][33] and hybrid DBR VCSELs. [34][35][36][37][38][39][40] The later consists of growing the n-side DBR (n-DBR) epitaxially, while dielectric layers are deposited for the p-side DBR (p-DBR).…”

Section: Motivation For Iii-nitride Tunnel Junction Intracavity Contactsmentioning

confidence: 99%

“…Dual dielectric DBR VCSELs, on the other hand, have dielectric n-DBRs and p-DBRs. This is typically achieved using a flip-chip design, [23][24][25][26][27][28][29][30][31][32] however it has also been demonstrated recently using lateral epitaxial overgrowth (LAE). 33 The hybrid DBR is advantageous because of the high thermal conductivity of the epitaxial n-DBR layers, which improves heat dissipation from the active region of the device.…”

Section: Motivation For Iii-nitride Tunnel Junction Intracavity Contactsmentioning

confidence: 99%

Comparison of nonpolar III-nitride vertical-cavity surface-emitting lasers with tunnel junction and ITO intracavity contacts

et al. 2016

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We report on the lasing of III-nitride nonpolar, violet, vertical-cavity surface-emitting lasers (VCSELs) with IIInitride tunnel-junction (TJ) intracavity contacts and ion implanted apertures (IIAs). The TJ VCSELs are compared to similar VCSELs with tin-doped indium oxide (ITO) intracavity contacts. Prior to analyzing device results, we consider the relative advantages of III-nitride TJs for blue and green emitting VCSELs. The TJs are shown to be most advantageous for violet and UV VCSELs, operating near or above the absorption edge for ITO, as they significantly reduce the total internal loss in the cavity. However, for longer wavelength III-nitride VCSELs, TJs primarily offer the advantage of improved cavity design flexibility, allowing one to make the p-side thicker using a thick n-type III-nitride TJ intracavity contact. This offers improved lateral current spreading and lower loss, compare to using ITO and p-GaN, respectively. These aspects are particularly important for achieving high-power CW VCSELs, making TJs the ideal intracavity contact for any III-nitride VCSEL. A brief overview of III-nitride TJ growth methods is also given, highlighting the molecular-beam epitaxy (MBE) technique used here. Following this overview, we compare 12 µm aperture diameter, violet emitting, TJ and ITO VCSEL experimental results, which demonstrate the significant improvement in differential efficiency and peak power resulting from the reduced loss in the TJ design. Specifically, the TJ VCSEL shows a peak power of ~550 µW with a threshold current density of ~3.5 kA/cm 2 , while the ITO VCSELs show peak powers of ~80 µW and threshold current densities of ~7 kA/cm 2 .

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Demonstration of Blue and Green GaN-Based Vertical-Cavity Surface-Emitting Lasers by Current Injection at Room Temperature

Cited by 177 publications

References 17 publications

Wurtzite spin lasers

Wurtzite spin lasers

Progress and challenges in electrically pumped GaN-based VCSELs

Comparison of nonpolar III-nitride vertical-cavity surface-emitting lasers with tunnel junction and ITO intracavity contacts

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