Traps in AlGaN∕GaN∕SiC heterostructures studied by deep level transient spectroscopy

Fang, Z-Q.; Look, David C.; Kim, D. H.; Adesida, I.

doi:10.1063/1.2126145

Cited by 101 publications

(72 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…From the two figures, we can see that both traps H 1 in the low-͓C͔ SBD and A 1 in the high-͓C͔ SBD increase with increasing t P , exhibiting logarithmic dependence, as shown in the inset figures. This kind of dependence, as reported previously for trap A 1 in the MOCVD-grown AlGaN/GaN heterostructure, 3 is an indication of the association of both traps H 1 and A 1 in AlGaN/ GaN with extended defects, such as threading dislocations. Traps A x and A 1 in the low-͓C͔ SBD and traps A 2 and H 2 ͑only half of H 2 was observed͒ in the high-͓C͔ SBD also appear to be associated with extended defects, since their DLTS signals show a strong t P dependence.…”

Section: Figsupporting

confidence: 52%

“…These values are similar to those observed for trap A 1 , previously reported by our laboratory for AlGaN/GaN SBDs from other source. 3 Activation energy of 0.9 eV for trap A x was found in AlGaN/GaN SBDs studied recently in our laboratory. 9 AlGaN/GaN SBDs as well.…”

Section: Figmentioning

confidence: 99%

“…A logarithmic dependence of DLTS signal with t p indicates that a given trap is related to extended defects ͑e.g., threading dislocations͒. 3 …”

Section: Methodsmentioning

confidence: 99%

“…Activation energy for traps A 3 and H 2 cannot be accurately determined. Because of their peak temperatures at T Ͼ 500 K, they must have activation energies higher than 1.2 eV, with an estimated value of ϳ1.3 eV for the A 3 .…”

Section: Figmentioning

confidence: 99%

“…Early studies revealed that gate lag and drain current collapse in HFET devices were related to traps in the AlGaN surface and GaN buffer layers. 1 Many techniques, such as photoionization spectroscopy, 2 deep level transient spectroscopy ͑DLTS͒, 3 deep level optical spectroscopy ͑DLOS͒, 4,5 and current-DLTS on HFETs, 6 have been used to study traps in AlGaN/GaN structures. Carbon is a common residual impurity in unintentionally doped ͑UID͒ GaN buffer layers grown by metalorganic chemical vapor deposition ͑MOCVD͒ but the carbon concentration and resistivity in these layers can be controlled by growth pressure.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Deep traps in AlGaN/GaN heterostructures studied by deep level transient spectroscopy: Effect of carbon concentration in GaN buffer layers

Fang

Claflin

Look

et al. 2010

Journal of Applied Physics

Self Cite

101

View full text Add to dashboard Cite

Electrical properties, including leakage currents, threshold voltages, and deep traps, of AlGaN/GaN heterostructure wafers with different concentrations of carbon in the GaN buffer layer, have been investigated by temperature dependent current-voltage and capacitance-voltage measurements and deep level transient spectroscopy ͑DLTS͒, using Schottky barrier diodes ͑SBDs͒. It is found that ͑i͒ SBDs fabricated on the wafers with GaN buffer layers containing a low concentration of carbon ͑low-͓C͔ SBD͒ or a high concentration of carbon ͑high-͓C͔ SBD͒ have similar low leakage currents even at 500 K; and ͑ii͒ the low-͓C͔ SBD exhibits a larger ͑negative͒ threshold voltage than the high-͓C͔ SBD. Detailed DLTS measurements on the two SBDs show that ͑i͒ different trap species are seen in the two SBDs: electron traps A x ͑0.9 eV͒, A 1 ͑0.99 eV͒, and A 2 ͑1.2 eV͒, and a holelike trap H 1 ͑1.24 eV͒ in the low-͓C͔ SBD; and electron traps A 1 , A 2 , and A 3 ͑ϳ1.3 eV͒, and a holelike trap H 2 ͑Ͼ1.3 eV͒ in the high-͓C͔ SBD; ͑ii͒ for both SDBs, in the region close to GaN buffer layer, only electron traps can be detected, while in the AlGaN/GaN interface region, significant holelike traps appear; and iii͒ all of the deep traps show a strong dependence of the DLTS signal on filling pulse width, which indicates they are associated with extended defects, such as threading dislocations. However, the overall density of electron traps is lower in the low-͓C͔ SBD than in the high-͓C͔ SBD. The different traps observed in the two SBDs are thought to be mainly related to differences in microstructure ͑grain size and threading dislocation density͒ of GaN buffer layers grown at different pressures.

show abstract

Section: Figsupporting

confidence: 52%

Section: Figmentioning

confidence: 99%

“…A logarithmic dependence of DLTS signal with t p indicates that a given trap is related to extended defects ͑e.g., threading dislocations͒. 3 …”

Section: Methodsmentioning

confidence: 99%

Section: Figmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Deep traps in AlGaN/GaN heterostructures studied by deep level transient spectroscopy: Effect of carbon concentration in GaN buffer layers

Fang

Claflin

Look

et al. 2010

Journal of Applied Physics

Self Cite

101

View full text Add to dashboard Cite

show abstract

Correlation of on‐wafer 400 V dynamic behavior and trap characteristics of GaN‐HEMTs

Imada

Piedra

Kikkawa

et al. 2014

Physica Status Solidi (a)

View full text Add to dashboard Cite

A method for identifying the critical traps for the dynamic behavior of gallium nitride high electron mobility transistors (GaN-HEMTs) is described. This method provides information on where the critical traps are located in the horizontal direction. At first, the on-wafer 400 V dynamic behavior of a GaN-HEMT was measured. Acceptor-like trap behavior with 0.14 eV activation energy was observed using conductance analysis. Next, trap characterization was achieved using the capacitance and series conductance transients of a comb-style Schottky barrier diode after electrical stress. Several different biases were applied to determine the locations of the detected traps, because depletion area edges can change upon imposition of different biases. Notably, 0.18 eV acceptor-like trap behavior below the Schottky electrode, 0.44 eV donor-like trap behavior in the access region, and 0.5eV acceptor-like trap behavior in access region were observed. By correlating these diode results with HEMT results, it was concluded that the critical trap behavior likely occurs below the gate electrode in HEMT. As a conclusion, the information obtained with this method should provide useful information for the improvement of device processes.

show abstract

Nanoscale fissure formation in Al_xGa_1–xN/GaN heterostructures and their influence on Ohmic contact formation

Smith¹,

Thomson

Zubialevich³

et al. 2016

Physica Status Solidi (a)

View full text Add to dashboard Cite

Nanoscale surface fissures on AlxGa1–xN/GaN (15 nm/1 µm) heterostructures grown by metalorganic vapour phase epitaxy (MOVPE) were imaged using tapping‐mode atomic force microscopy (AFM) and electron channelling contrast imaging (ECCI). Fissure formation was linked to threading dislocations, and was only observed in samples cooled under H2 and NH3, developing with increasing barrier layer Al content. No strain relaxation was detected regardless of fissure formation up to barrier layer Al composition fractions of x = 0.37. A reduction of measured channel carrier density was found in fissured samples at low temperature. This instability is attributed to shallow trap formation associated with fissure boundaries. For Ti/Al/Ni/Au Ohmic contact formation to high Al content barrier layers, fissures were found to offer conduction routes to the 2DEG that allow for low resistance contacts, with fissure‐free samples requiring additional optimisation of the metal stack and anneal conditions to achieve contact resistivity of order those measured in fissured samples. In addition, the effects of fissures were found to be detrimental to thermal stability of sheet and contact resistance, suggesting that fissure formation compromises the integrity of the 2DEG.

show abstract

Traps in AlGaN∕GaN∕SiC heterostructures studied by deep level transient spectroscopy

Cited by 101 publications

References 16 publications

Deep traps in AlGaN/GaN heterostructures studied by deep level transient spectroscopy: Effect of carbon concentration in GaN buffer layers

Deep traps in AlGaN/GaN heterostructures studied by deep level transient spectroscopy: Effect of carbon concentration in GaN buffer layers

Correlation of on‐wafer 400 V dynamic behavior and trap characteristics of GaN‐HEMTs

Nanoscale fissure formation in Al_xGa_1–xN/GaN heterostructures and their influence on Ohmic contact formation

Contact Info

Product

Resources

About

Traps in AlGaN∕GaN∕SiC heterostructures studied by deep level transient spectroscopy

Cited by 101 publications

References 16 publications

Deep traps in AlGaN/GaN heterostructures studied by deep level transient spectroscopy: Effect of carbon concentration in GaN buffer layers

Deep traps in AlGaN/GaN heterostructures studied by deep level transient spectroscopy: Effect of carbon concentration in GaN buffer layers

Correlation of on‐wafer 400 V dynamic behavior and trap characteristics of GaN‐HEMTs

Nanoscale fissure formation in AlxGa1–xN/GaN heterostructures and their influence on Ohmic contact formation

Contact Info

Product

Resources

About

Nanoscale fissure formation in Al_xGa_1–xN/GaN heterostructures and their influence on Ohmic contact formation