Indium as an efficient ohmic contact to N-face <i>n</i>-GaN of GaN-based vertical light-emitting diodes

Moon, Sangook; Son, Jun Ho; Choi, Kyeongdal; Lee, Jong‐Lam; Jang, Ho Won

doi:10.1063/1.3662421

Cited by 20 publications

(5 citation statements)

References 19 publications

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“…5. Previously Moon et al 18) investigated the electrical characteristics of 200-nmthick In contacts on N-polar n-GaN. Based on their XPS results, they attributed the ohmic behavior to the formation of an interfacial InN phase, creating donor-like N vacancies in n-GaN.…”

Section: Resultsmentioning

confidence: 99%

“…Thus, in this study, we investigated the effects of thin In interlayers on the electrical properties of Ti=Al=Au contacts. In other words, unlike previous studies where 200-nm-thick In layers were used, 18) the In layer thickness in our study varied from 3 to 10 nm. X-ray photoemission spectroscopy (XPS) examinations were performed to elucidate the annealing dependence of the electrical behavior of the samples.…”

Section: Introductionmentioning

confidence: 99%

“…6) It has been shown that the electrical characteristics of metal contacts to N-polar n-GaN are different from those of contacts to Ga-polar n-GaN. In other words, unlike contacts to Ga-polar n-GaN, 7,8) ohmic contacts to N-polar n-GaN [9][10][11][12][13][14][15][16][17][18] are not easy to form. For instance, Kwak et al, 10) who investigated the effect of crystal polarity on the electrical properties of Ti=Al contacts to hydride-vapor-phase-epitaxy freestanding n-GaN substrates, showed that the Ti=Al contacts on Ga-polar n-GaN substrate became ohmic after annealing at temperatures higher than 600 °C for 30 s, while the contacts on N-polar n-GaN exhibited non-ohmic behavior with high Schottky barrier heights (SBHs) larger than 1 eV.…”

Section: Introductionmentioning

confidence: 99%

“…In addition, a 200-nm-thick In layer with a low work function (∼4.12 eV 19) ) was also used to form a low resistance ohmic contact to N-polar n-GaN. 18) The In single contacts had a contact resistivity of ∼10 −5 Ω cm 2 after annealing at 300 °C. The annealing-induced electrical enhancement was ascribed to the formation of an interfacial InN layer.…”

Section: Introductionmentioning

confidence: 99%

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Thermally stable Ti/Al-based ohmic contacts to N-polar n-GaN by using an indium interlayer

Kim

Han

Seong

2016

Jpn. J. Appl. Phys.

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The electrical properties of In/Ti/Al/Au contacts to N-polar n-GaN (n d = 5 × 1018 cm−3) for high-power vertical light-emitting diodes were investigated at various thicknesses of the In layer, and compared with those of Ti/Al/Au contacts. Before annealing, both the Ti/Al/Au and In/Ti/Al/Au contacts were ohmic. After annealing at 300 °C for 1 min, all of the samples exhibited some degradation of their electrical properties, although the In/Ti/Al/Au samples were more thermally stable. After annealing at 300 °C for 60 min, the Ti/Al/Au contacts became non-ohmic, while the In (5 nm)/Ti/Al/Au contacts remained ohmic with a contact resistivity of 2.6 × 10−4 Ω cm2. X-ray photoemission spectroscopy (XPS) results showed that, for all of the samples, annealing caused an increase in the content of interfacial oxygen. Based on the XPS and electrical results, the annealing dependence of the electrical characteristics of In/Ti/Al/Au contacts are described and discussed.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Thermally stable Ti/Al-based ohmic contacts to N-polar n-GaN by using an indium interlayer

Kim

Han

Seong

2016

Jpn. J. Appl. Phys.

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“…However, different from Ga face, the ohmic contact on N-face has the disadvantages of larger contact resistivity and poor thermal stability, which seriously affect the performance of power devices [13][14][15][16]. The contact resistivity of the N-face is two orders of magnitude than that of Ga-face, and it is degraded at 300 • C. Various efforts have been done to make good ohmic contact to N-face: (a) changing metal systems to form ohmic contact [17][18][19], (b) surface pretreatments before the deposition of ohmic contact metals [20][21][22], (c) current blocking layer between metal and surface [23]. Kim et al found that O 2 plasma treatment can effectively reduce the total and sheet resistance of Ti/Al ohmic contact to N-face [24].…”

Section: Introductionmentioning

confidence: 99%

HVPE growth of bulk GaN with high conductivity for vertical devices

Xia¹,

Wang²,

Chen³

et al. 2020

Semicond. Sci. Technol.

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The electrical properties of gallium nitride (GaN) substrate are crucial to the performance of vertical power devices. Bulk GaN substrates with carrier concentrations in the range from 6.7 × 1017 to 1.7 × 1019 cm−3 are grown by hydride vapor phase epitaxy. All samples show no obvious tensile stress regardless of the carrier concentration. Moreover, the mobility of Si-doped high-quality bulk GaN is superior to the GaN template with higher dislocation density at the same carrier concentration. The influence of carrier concentration on the performance of ohmic contact on N-face of Si-doped GaN is also carefully studied by circular transfer length measurement and rapid thermal annealing methods. The specific contact resistivity decreases monotonically with increase of carrier concentration, while it increases with the annealing temperature. The N-face contact becomes non-ohmic when the annealing temperature exceeds the limit value, which increases with the carrier concentration. The sample with carrier concentration of 1.7 × 1019 cm−3 still showed ohmic behavior after annealing at 450 °C. These results are not only useful to improve the electrical properties of N-type bulk GaN substrate, but also provide a potential solution for improving the efficiency of vertical devices in the future.

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Evolution of Electrically Active Defects in n‐GaN During Heat Treatment Typical for Ohmic Contact Formation

Boturchuk

Scheffler

Larsen

et al. 2017

Physica Status Solidi (a)

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Ohmic contact formation to n‐type GaN often involves high temperature steps, for example sintering at about 800 °C in the case of Ti‐based contacts. Such processing steps might cause changes in the distribution, concentration, and properties of the defects. The present work aims at contributing to the knowledge about defect evolution in GaN upon processing at different temperatures. The processing temperatures are selected according to fabrication procedures for commonly used ohmic contacts to n‐GaN: 300 °C (In‐based), 550 °C (Ta‐based), and 800 °C (Ti‐based). Properties and concentration of the defects are studied by the means of deep level transient spectroscopy (DLTS). Changes in carrier capture kinetics are monitored with varying filling pulse duration.

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Indium as an efficient ohmic contact to N-face n-GaN of GaN-based vertical light-emitting diodes

Cited by 20 publications

References 19 publications

Thermally stable Ti/Al-based ohmic contacts to N-polar n-GaN by using an indium interlayer

Thermally stable Ti/Al-based ohmic contacts to N-polar n-GaN by using an indium interlayer

HVPE growth of bulk GaN with high conductivity for vertical devices

Evolution of Electrically Active Defects in n‐GaN During Heat Treatment Typical for Ohmic Contact Formation

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