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

Rychetsky, Monir; Koslow, Ingrid; Wernicke, Tim; Raß, Jens; Hoffmann, Veit; Weyers, M.; Kneissl, Michael

doi:10.1002/pssb.201552407

Cited by 9 publications

(7 citation statements)

References 26 publications

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“…5). This may bedue to a p ++ layer with lower amount of Mg compared to (0001) [as also indicated by recent results on (2021) 21 ]. Another reason could be the much higher tendency of (1122) to incorporate oxygen, i.e.…”

Section: Doping and Contactsmentioning

confidence: 57%

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Comparative study of (0001) and InGaN based light emitting diodes

Pristovsek

Humphreys

Bauer

et al. 2016

Jpn. J. Appl. Phys.

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We have systematically investigated the doping of (1122) with Si and Mg by metal-organic vapour phase epitaxy for light emitting diodes (LEDs). By Si doping of GaN we reached electron concentrations close to 10 20 cm −3 , but the topography degrades above mid 10 19 cm −3. By Mg doping we reached hole concentrations close to 5×10 17 cm −3 , using Mg partial pressures about 3× higher than those for (0001). Exceeding the maximum Mg partial pressure led to a quick degradation of the sample. Low resistivities as well as high hole concentrations required a growth temperature of 900 • C or higher. At optimised conditions the electrical properties as well as the photoluminescence of (1122) p-GaN were similar to (0001) p-GaN. The best ohmic p-contacts were achieved by NiAg metallisation. A single quantum well LED emitting at 465 nm was realised on (0001) and (1122). Droop (sub-linear increase of the light output power) occurred at much higher current densities on (1122). However, the light output of the (0001) LED was higher than that of (1122) until deep in the droop regime. Our LEDs as well as those in the literature indicate a reduction in efficiency from (0001) over semi-polar to non-polar orientations. We propose that reduced fields open a loss channel for carriers.

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Section: Doping and Contactsmentioning

confidence: 57%

“…It was previously reported that the (1122) surface needs a 2-3 times higher Cp 2 Mg flow rate than the (0001) surface to obtain a similar Mg incorporation. 10,20,21 Hence, first we targeted the Cp 2 Mg flow rate. When a certain Cp 2 Mg flow rate was exceeded, we observed many dark spots in the optical microscope [ Fig.…”

Section: Doping and Contactsmentioning

confidence: 99%

Comparative study of (0001) and InGaN based light emitting diodes

Pristovsek

Humphreys

Bauer

et al. 2016

Jpn. J. Appl. Phys.

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“…Ni/Au electrodes were evaporated on the surface of the samples after annealing activation. [12,13] To realize good ohmic contact, the electrodes were annealed at 600 °C in air atmosphere for 60 s. I-V measurements were carried out to test the contact between the electrode and p-GaN. As shown in Figure 5, the p-GaN layer grown on the c-plane FS-GaN substrate can achieve a good ohmic contact with the annealed Ni/Au electrode.…”

Section: Resultsmentioning

confidence: 99%

Influence of Polarities of GaN Substrates on Surface Morphologies and Physical Properties of Epitaxial Mg‐Doped GaN Films Grown by MOCVD

Wei

Wang

et al. 2022

Physica Status Solidi (a)

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Herein, the influence of free‐standing GaN (FS–GaN) substrates with different polarities on the surface morphologies and physical properties of epitaxial Mg‐doped GaN films grown by metal–organic chemical vapor deposition (MOCVD) is investigated. For the Mg‐doped GaN films grown on polar, semipolar, and nonpolar FS–GaN substrates, their surface morphologies vary greatly, which is attributed to the different surface states and growth modes. All films show high crystalline quality and are basically in a stress‐free state. For polar p‐GaN, good ohmic contact is achieved with Ni/Au electrode. For semipolar and nonpolar p‐GaN, there are obvious contact barriers between the p‐GaN and the metal electrodes, and the Mg‐doping concentration may be higher than that of the c‐plane epitaxial GaN according to the intensity ratio of the band edge peak with respect to the ultraviolet luminescence peak in photoluminescence spectra, which will be investigated in the near future.

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“…The samples were grown on commercial 3.5 μm standard Si doped GaN ( n = 1.7 ×10 18 cm −3 ) on (0001) direction sapphire substrates in a T‐shape horizontal flow low‐pressure metal organic vapor phase epitaxy (MOVPE) reactor . First, the epitaxial growth of the p‐GaN layer was optimized which is a crucial for achieving good quality ohmic contact to p‐GaN . Samples with 150 nm thick nominally doped p‐GaN followed by 50 nm thick highly doped p‐GaN were grown on the templates.…”

Section: Methodsmentioning

confidence: 99%

Investigation of p-contact performance for indium rich InGaN based light emitting diodes and solar cells

Alam

Haas

et al. 2016

Phys. Status Solidi A

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We report on the optimization of p-GaN layers for high indium (In) content InGaN applications by optimizing temperature, precursor CP 2 Mg flow rate and III/V ratio and report also on the optimization of p-contact performance. Using MOVPE, a 150 nm thick p-type GaN with moderate Mg doping and a 50 nm contact layer with high Mg doping concentration were grown on standard GaN templates at growth temperatures in the range of 850-1000 8C. Hall measurement yields hole concentration of 4.8 Â 10 17 cm À3 for the optimized sample. SIMS shows Mg concentration of 1.7 Â 10 20 cm À3 on average in the heavily doped and 4 Â 10 19 cm À3 on average in the moderately doped p-GaN layer for the optimized p-GaN. A multilayer Pd/Ag/Ni/Au metal contact has been deposited on this p-GaN and studied using the CTLM technique. Optimization of both p-GaN layers and p-contact processing led to a low resistance contact with specific contact resistivity of 6 Â 10 À4 Ω cm 2 . We believe, the very high Mg concentration of the surface layer in intimate contact with the contact metal reduces the Schottky barrier height and band bending. This optimization of p-GaN is an important step towards high efficiency green LEDs and solar cells.

show abstract

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

Cited by 9 publications

References 26 publications

Comparative study of (0001) and InGaN based light emitting diodes

Comparative study of (0001) and InGaN based light emitting diodes

Influence of Polarities of GaN Substrates on Surface Morphologies and Physical Properties of Epitaxial Mg‐Doped GaN Films Grown by MOCVD

Investigation of p-contact performance for indium rich InGaN based light emitting diodes and solar cells

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