Investigation of Defect Characteristics and Carrier Transport Mechanisms in GaN Layers With Different Carbon Doping Concentration

Wang, Hongyue; Hsu, Po-Yang; Zhao, Ming; Simoen, Eddy; Sibaja-Hernandez, A.; Wang, Jinyan

doi:10.1109/ted.2020.3025261

Cited by 9 publications

(5 citation statements)

References 43 publications

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“…Electron traps with E1 and E2 were commonly observed in undoped, 18 intentionally n-type-doped, 19 and carbon-doped GaN layers, [9][10][11][12][13][14]20 which means that they are intrinsic defects not related to doping impurities. By changing the pulse duration t P , one can show that the amplitude of E1 increases linearly with ln(t P ) (Fig.…”

Section: A V P Bias At Off-statementioning

confidence: 99%

Analysis of semi-insulating carbon-doped GaN layers using deep-level transient spectroscopy

Wang

Hsu

Zhao

et al. 2021

Journal of Applied Physics

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Electrically active defects in carbon-doped GaN layers were studied with a metal/carbon-doped GaN (GaN:C)/Si-doped GaN (GaN:Si) MIS structure. The GaN:C layers were grown with three different carbon doping concentrations (NC). A semi-vertical metal/semi-insulator/n-type semiconductor (MIS) device was fabricated to perform deep-level transient spectroscopy (DLTS) measurements. Two electron traps E1 and E2 with energy level at EC − (0.22–0.31) eV and EC − (0.45–0.49) eV were observed. E1 and E2 are associated with a nitrogen vacancy VN-related defect in the strain field of extended defects and a nitrogen antisite defect, respectively. By changing the reverse bias voltage of the DLTS measurement, the location and relative defect concentration of the E1 and E2 traps could be verified. A dominant electron trap E3 with an unusual capture cross section was only observed in devices with an NC = 2 × 1019 cm−3 GaN:C layer. This may charge carriers from a defect band and lead to the charge redistribution in the GaN:C layer when forward biased. A hole trap H1 with energy level at EV + 0.47 eV was found for the pulse bias in the forward ON-state. H1 is suggested to correspond with the CN induced 0/+ donor level. By analyzing the schematic band diagrams across the MIS structure, the carrier transport and defect charging mechanisms underlying the DLTS transient measurements are illustrated. The identification of the trap states in the carbon-doped GaN with different NC gives further understanding on the carbon doping impact on electric characteristics of GaN power devices made on Si substrates.

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Section: A V P Bias At Off-statementioning

confidence: 99%

Analysis of semi-insulating carbon-doped GaN layers using deep-level transient spectroscopy

Wang

Hsu

Zhao

et al. 2021

Journal of Applied Physics

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“…It was found that the high carbon-doped concentration (high carbon) 10 19 cm −3 has 171 V higher breakdown voltage than (low carbon) 10 18 cm −3 at 1 A cm −2 , Table 1. Carrier transport mechanisms [9][10][11][12][13][14][15][16][17][18].…”

Section: Resultsmentioning

confidence: 99%

“…Here, we consider that carbon would replace N or Ga, possibly acting as acceptor or donor [6][7][8]. At present, there are several leakage mechanisms on GaN-based epitaxial layers as shown in table 1 [9][10][11][12][13][14][15][16][17][18]. Among them, Zhou et al [9] have used accepted and donored ionization to analyze doped GaN high-electron-mobility transistors (HEMTS) leakage mechanism, and found space-charge-limited current (SCLC) models [9,10] make a key role.…”

Section: Introductionmentioning

confidence: 99%

“…At present, there are several leakage mechanisms on GaN-based epitaxial layers as shown in table 1 [9][10][11][12][13][14][15][16][17][18]. Among them, Zhou et al [9] have used accepted and donored ionization to analyze doped GaN high-electron-mobility transistors (HEMTS) leakage mechanism, and found space-charge-limited current (SCLC) models [9,10] make a key role. Yacoub [11] found leakage current mechanism is Poole-Frenkel (PF) conduction [12][13][14] at positively biased, and it is SCLC modes at reverse voltage too.…”

Section: Introductionmentioning

confidence: 99%

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The role of point defects related with carbon impurity on the kink of log J–V in GaN-on-Si epitaxial layers

Song¹,

Liu²,

Yang³

et al. 2022

Nanotechnology

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Carbon impurity as point defects makes key impact on the leakage in GaN-on-Si structures. GaN-based epitaxial layers with different point defects by changing carbon-doped concentration were used to investigate the point defects behavior. It was found that leakage mechanisms correspond with space-charge-limited current models at low voltages, and after 1st kink, electron injection from silicon to GaN and PF conduction play a key role in the leakage of both point defects case with low carbon and high carbon doped. In addition, high carbon in GaN-on-Si epitaxial layers obtained lower leakage and larger breakdown voltage. The slope of log J-V has two kinks and effective energy barrier Ea has two peaks, 0.4247eV at about 300V and 0.3485eV at about 900V, respectively, which is related to accepted states and donor states related with carbon impurity. While the slope of log J-V has one kink and effective energy barrier Ea has one peak, 0.4794eV at about 400V of low carbon in GaN-on-Si epitaxial layers, indicating only Field-induced accepted ionized makes impact on leakage. The comparative results of more donor trap density in high carbon indicate point defects related with carbon impurity play a key role in the kinks of log J-V slope.

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“…On the one hand, the commonly adopted method to reduce buffer leakage for power applications is to introduce carbon atoms in GaN, which may result in undesired trapping effects [4][5][6]. Many research groups have made a lot of effort to achieve a balance between breakdown voltage (BV) and trapping effects, such as optimizing the carbon concentration in GaN buffer [7][8][9], alternating carbon doping techniques [9], incorporating appropriate donor impurities to compensate carbon [10], removing local substrate [11], and so on. On the other hand, the structure of the buffer layer affects the trap density and the depletion of two-dimensional electron gas (2DEG).…”

Section: Introductionmentioning

confidence: 99%

Enhanced breakdown voltage and dynamic performance of GaN HEMTs with AlN/GaN superlattice buffer

Chen

Zhong

Yan

et al. 2023

J. Phys. D: Appl. Phys.

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The characteristics of AlGaN/GaN HEMT buffer structure are studied and optimized by employing AlN/GaN superlattice structure. Through vertical leakage analysis and back-gate measurement, combined with Silvaco-TCAD simulation, the influence of buffer traps is analyzed on the carrier transport behaviors and electrical performance for superlattice buffer structures under a high electric field. The AlN/GaN superlattice buffer structures are further optimized with various AlN/GaN thickness ratio and their total thickness through both simulation and experimental studies. As a result, a high breakdown voltage of up to 1.3 kV with a maximum breakdown electric field of 2.8 MV/cm has been achieved. Moreover, the buffer trapping effect is dramatically suppressed, leading to a minimum drop of channel current for the optimized sample, in which donor traps are found to play a positive role in the device dynamic characteristics.

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Investigation of Defect Characteristics and Carrier Transport Mechanisms in GaN Layers With Different Carbon Doping Concentration

Cited by 9 publications

References 43 publications

Analysis of semi-insulating carbon-doped GaN layers using deep-level transient spectroscopy

Analysis of semi-insulating carbon-doped GaN layers using deep-level transient spectroscopy

The role of point defects related with carbon impurity on the kink of log J–V in GaN-on-Si epitaxial layers

Enhanced breakdown voltage and dynamic performance of GaN HEMTs with AlN/GaN superlattice buffer

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