GaN-Based Light Emitting Diodes with Tunnel Junctions

Takeuchi, Tetsuya; Hasnain, G.; Corzine, S.; Hueschen, M. R.; Schneider, Richard; Kocot, Chris; Blomqvist, Mats; Chang, Ying‐Lan; Lefforge, D.; Krames, Mike; Cook, Lou W.; Stockman, S. A.

doi:10.1143/jjap.40.l861

Cited by 101 publications

(58 citation statements)

References 19 publications

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“…First of all, growing n-GaN on p-GaN via metalorganic chemical-vapor deposition (MOCVD), results in highly resistive TJ contacts. [49][50][51][52][53] This is due to p-GaN hydrogen repassivation during the n-GaN TJ growth, and the intrinsic doping limits of MOCVD grown n-GaN. 54 Additionally, growing such an n-GaN layer prevents hydrogen from escaping from the p-GaN during the post-growth thermal activation of Mg dopants.…”

Section: Overview Of Iii-nitride Tunnel Junctionsmentioning

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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Section: Overview Of Iii-nitride Tunnel Junctionsmentioning

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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“…The output power of TJ LED was found to be higher than the reference LED with semitransparent top contact, consistent with previous observations. 21,22,[24][25][26][27] The forward voltage of InGaN TJ LED is listed in Table 1 below. Although these results represent the lowest reported voltage drop in TJ LEDs, the forward voltage is still high and needs to be lowered further.…”

Section: Tunnel Junction Ledmentioning

confidence: 99%

III-nitride tunnel junctions for efficient solid state lighting

2014

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We discuss the design and demonstration ultra-low resistance III-nitride tunnel junctions, and how tunnel junctions could solve the long-standing problem of efficiency droop in solid state lighting. We have used nanoscale band engineering based on polarization and mid-gap states to reduce tunneling resistance by four orders of magnitude. We will discuss experimental demonstration of highly efficient tunnel junctions (resistivity ~ 0.1 mOhm-cm 2 ) in PN junctions, p-contact free LEDs, and multiple junction structures. Finally we will show how tunneling based carrier regeneration in multiple active region cascade LEDs could help to enable low current, high voltage operation to overcome the efficiency droop problem.

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“…The active region is assumed to be composed of five 3.5 nm In 0.15 Ga 0.85 N quantum wells (QWs) separated by the 3.5 nm In 0.02 Ga 0.98 N barriers. Therefore, as compared with standard GaAs-based VCSELs, we suggest additionally employing the tunnel junction [12,13] (the 30 nm n ++ -GaN layer and the 15 nm p ++ -In 0.2 Ga 0.8 N layer). The active region is sandwiched by GaN spacers, the n-type 62.82 nm one and the p-type 75.16 nm one.…”

Section: The Gan Vcsel Structurementioning

confidence: 99%

Optical Design of Vertical‐Cavity Lasers

Nakwaski

Czyszanowski

Sarzała

2007

Nitride Semiconductor Devices: Principles and Simulation

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Based on Micro-Opto-Electro-Mechanical System (MOEMS) technology, vertical cavity devices with an air-gap enable very efficient ultra-wide continuous tuning with only a single control parameter. The vertical cavity filters and Lasers consist of an air-gap cavity embedded between two highly reflective Bragg mirrors. Vertical Cavity Surface Emitting Lasers (VCSELs) have an active layer additionally integrated in the cavity. The ultra-wide continuous tuning is achieved by micro-electromechanical actuation of the mirror membranes. Our research activities concentrated on Bragg mirror material system with InP/air-gap mirror structures. The resonator quality depends on the refractive index contrast between the Bragg mirror layer materials and on the number of periods. The advantage of the semiconductor/air-gap system is the very high refractive index contrast ensuring a high reflectivity of more than 99.8% with only three layer periods. The semiconductor/air-gap structures forming the membranes of one Bragg mirror are n-doped while the other mirror membranes are p-doped forming a diode structure. Due to device miniaturization very efficient tuning is achieved by electrostatic actuation. The investigations presented focus on an InP/air-gap Fabry-Pérot-filter for  air =1.55µm with an air-gap cavity thickness equal to a multiple of ½  air embedded between two InP/air Bragg mirrors. The InP membranes have a thickness of of ¾  InP , the air-gaps in between are ¼ air thick. The tuning behaviour is determined by the mechanical flexibility of the membranes and by the optical properties of the vertical cavity. The electrostatic deflection due to a reverse voltage is calculated with FEM simulations incorporating the effect of stress in the membranes. The results of the model calculations compared very well with measured values. This study describes the optical micro-electromechanical design of the novel low cost device structure applicable in optical filters, vertical cavity surface emitting lasers (VCSELs) and a host of other optical applications. We also present a solution to one of the most challenging problems in the design of micro-electromechanical devices consisting of thin-walled structures -that is residual stress. Residual stress alters device characteristics if not taken into consideration during design and characterisation.

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GaN-Based Light Emitting Diodes with Tunnel Junctions

Cited by 101 publications

References 19 publications

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

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

III-nitride tunnel junctions for efficient solid state lighting

Optical Design of Vertical‐Cavity Lasers

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