Demonstration of low resistance ohmic contacts to p-type (202̄1̄) GaN

Yonkee, Benjamin P.; Leonard, John T.; DenBaars, Steven P.; Speck, J. S.; Nakamura, Shuji

doi:10.1088/0268-1242/30/7/075007

Cited by 12 publications

(12 citation statements)

References 20 publications

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“… Ag contacts showed very high performance (∼10 −5 Ω cm 2 ) in combination with La additives. In the semipolar case, ohmic contacts were reported on (11–22) based on Zn/Ag contacts and on (20–2–1) based on Ni/Au . In Ref.…”

Section: Resultsmentioning

confidence: 99%

“…In Ref. , palladium and indium tin oxide contacts have shown very high performance on (20–2–1) (∼10 −4 Ω cm 2 ). This suggests that further optimization of growth conditions in our p ++ cap layer might still possibly yield a lower contact resistance, or that alternative contact metals should be investigated in the future.…”

Section: Resultsmentioning

confidence: 99%

“…To achieve ohmic contacts, a thin highly doped p ++ ‐GaN cap layer is typically necessary. Although many studies exist for contacts on c ‐plane GaN:Mg, there are only a few studies on ohmic contacts on nonpolar nitrides and semipolar nitrides .…”

Section: Introductionmentioning

confidence: 99%

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Impact of acceptor concentration on the resistivity of Ni/Au p‐contacts on semipolar (20–21) GaN:Mg

Rychetsky

Koslow

Wernicke

et al. 2015

Physica Status Solidi (b)

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The p‐type doping of GaN with Mg, in particular doping of p++ cap layers and its influence on the resistivity of Ni/Au contacts on semipolar (20–21) GaN, has been investigated. For this purpose, we have compared GaN:Mg grown on several semipolar and polar orientations with respect to the acceptor concentration NA measured by electrochemical capacitance voltage techniques. For the same Mg precursor flow and Mg/III ratio, we observe very similar acceptor densities NA of up to 1 × 1019 cm−3 for (0001), (20–21), (20–2–1), and (11–22) GaN:Mg. Furthermore, the impact of the II/III ratio for the p++ cap layer (NA > 1 × 1019 cm−3) on I–V characteristics of Ni/Au (20 nm/30 nm) contacts on (20–21) oriented GaN:Mg has been investigated. Ohmic I–V characteristics were observed for Mg/III ratios >1 × 10−2. Specific contact resistivities as low as 2.4 × 10−3 Ω cm2 could be achieved. Inclusion of this p++ cap layer resulted in reduced turn on voltages in light emitting diodes with 450 nm emission wavelength.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Impact of acceptor concentration on the resistivity of Ni/Au p‐contacts on semipolar (20–21) GaN:Mg

Rychetsky

Koslow

Wernicke

et al. 2015

Physica Status Solidi (b)

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“…54 Furthermore, the MOCVD grown p ++ GaN layer was optimized in a method similar to that reported by B. P. Yonkee, et al. 61 The final optimized 14 nm p ++ GaN layer had a Mg doping concentration of ~2 × 10 20 cm -3…”

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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“…Electronic mail: changminlee86@gmail.com were grown followed by a 10 nm highly Mg-doped p þ -GaN contact layer. 28 The doping level of the n-GaN contact layer was optimized to obtain a low resistance topside n-type contact, which is essential for reducing the resistance of the device as well as enabling radio frequency (RF) measurements with ground-signal (GS) or ground-signal-ground (GSG) probe configurations.…”

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confidence: 99%

Dynamic characteristics of 410 nm semipolar (202¯1¯) III-nitride laser diodes with a modulation bandwidth of over 5 GHz

Lee

Zhang

Becerra

et al. 2016

Applied Physics Letters

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The dynamic characteristics of III-nitride multi-quantum well laser diodes (LDs) emitting at 410 nm were investigated. LDs were grown on semipolar (202¯1¯) bulk GaN substrates and fabricated into devices with cavity lengths ranging from 900 nm to 1800 nm. A 3-dB bandwidth of 5 GHz and 5 Gbit/s direct modulation with on-off keying were demonstrated, which were limited by the bandwidth of the photodetector used for the measurements. The differential gain of the LDs was determined to be 2.5 ± 0.5 × 10−16 cm2 by comparing the slope efficiency for different cavity lengths. Analysis of the frequency response showed that the K-factor, the gain compression factor, and the intrinsic maximum bandwidth were 0.33 ns, 7.4 × 10−17 cm3, and 27 GHz, respectively.

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Demonstration of low resistance ohmic contacts to p-type (202̄1̄) GaN

Cited by 12 publications

References 20 publications

Impact of acceptor concentration on the resistivity of Ni/Au p‐contacts on semipolar (20–21) GaN:Mg

Impact of acceptor concentration on the resistivity of Ni/Au p‐contacts on semipolar (20–21) GaN:Mg

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

Dynamic characteristics of 410 nm semipolar (202¯1¯) III-nitride laser diodes with a modulation bandwidth of over 5 GHz

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