Correlation of gate leakage and local strain distribution in GaN/AlGaN HEMT structures

Broas, Mikael; Graff, Andreas; Simon-Najasek, Michél; Poppitz, David; Altmann, Frank; Jung, Helmut; Blanck, H.

doi:10.1016/j.microrel.2016.07.050

Cited by 10 publications

(7 citation statements)

References 14 publications

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“…The performance of GaN‐based electronic devices (e.g., Schottky diodes, or high electron mobility transistors − HEMTs) can be affected by the defects E2/E3, which might introduce pathways for the leakage current . In addition, the 2‐dimensional electron gas (2DEG) in HEMTs could be depleted by the surface‐related defects E2/E3, thus deteriorating the power output of the transistors.…”

Section: Discussionmentioning

confidence: 99%

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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Section: Discussionmentioning

confidence: 99%

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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“…In GaN, gallium vacancies (V Ga ) and vacancy complexes form deep levels in the band-gap, [44,81,82] cause non-radiative recombination, [83] contribute to sub-bandgap optical absorption, [42] compensate n-type doping, [40] and have been associated with device degradation. [82,[84][85][86] Recently the formation of helical dislocations during heat treatment of ammonothermal GaN was associated with interaction of dislocations and vacancy defects. [45] The properties of gallium vacancies and their complexes with hydrogen (V Ga -H) have been calculated from first principles.…”

Section: Gallium Vacancies and Vacancy Clustersmentioning

confidence: 99%

“…The observed vacancy concentration is several orders of magnitude higher than what has been reported for HVPE grown material and is expected to have a significant effect on the material properties. In GaN, gallium vacancies (V Ga ) and vacancy complexes form deep levels in the band‐gap, cause non‐radiative recombination, contribute to sub‐bandgap optical absorption, compensate n‐type doping, and have been associated with device degradation . Recently the formation of helical dislocations during heat treatment of ammonothermal GaN was associated with interaction of dislocations and vacancy defects …”

Section: Defects In Ammonothermal Gallium Nitridementioning

confidence: 99%

Defects in Single Crystalline Ammonothermal Gallium Nitride

Suihkonen

Pimputkar

Sintonen

et al. 2017

Adv Elect Materials

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Native bulk gallium nitride (GaN) has emerged as an alternative for sapphire and silicon as a substrate material for III‐N devices. While quasi‐bulk GaN substrates are currently commercially available, single crystal GaN substrates are considered essential for future high performance light emitters and power devices. The ammonothermal method is currently considered one of the most feasible methods to grow large truly bulk crystals of GaN at low cost and high structural quality. High crystalline quality GaN substrates sliced from ammonothermally grown crystals have been demonstrated and utilized in homoepitaxy for III‐N devices. However, despite the high crystalline quality the properties of as‐grown ammonothermal GaN crystals and substrates are affected by the presence of impurities and other defects that hinder their use for device applications. Here, the main developments of ammonothermal growth of GaN and the effects of impurities, native point defects, and dislocations on the material properties are summarized. Additionally, measurement techniques that enable the evaluation of point defect concentration and low dislocation density distribution over a large area on bulk GaN substrates are reviewed.

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“…For example, gate leakage of HEMTs has been ascribed to the local stress intensity that promotes interdiffusion of the Schottky contact metallization. [14] Only a few studies have attempted to control intrinsic stress to show appreciable influence over radiation effects. [15,16] There is a need to extend these studies to specific types of radiation and stress.…”

Section: Introductionmentioning

confidence: 99%

Nanoscale Stress Localization Effects on the Radiation Susceptibility of GaN High‐Mobility Transistors

Rasel

Stepanoff

Haque

et al. 2022

Physica Rapid Research Ltrs

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Nanoscale localized mechanical stress fields develop unavoidably in microelectronic devices due to structural and processing aspects. Their global average is too small to influence bandgap or mobility, but it is proposed that stress localization can influence defect nucleation sites under radiation. This is investigated on gallium nitride high‐electron‐mobility transistors (GaN HEMTs). Using transmission electron microscopy, we spatially resolved the stress field in the AlGaN layer for both pristine and 10 Mrad gamma‐irradiated HEMTs. The quantitative nanobeam electron diffraction and geometric phase analysis indicate that tensile stressed localizations experience higher radiation‐induced strain. This finding is explained by the tensile stress dependence of the carrier concentration and mobility in the AlGaN layer. Since gamma radiation damage is inflicted by high‐energy electrons only, localized regions of higher tensile stress in the AlGaN layer are expected to be more susceptible to gamma rays.

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Correlation of gate leakage and local strain distribution in GaN/AlGaN HEMT structures

Cited by 10 publications

References 14 publications

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

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

Defects in Single Crystalline Ammonothermal Gallium Nitride

Nanoscale Stress Localization Effects on the Radiation Susceptibility of GaN High‐Mobility Transistors

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