The Influence of Traps on the Self-Heating Effect and THz Response of GaN HEMTs
This study systematically investigates the effects of trap concentration on self-heating and terahertz (THz) responses in GaN HEMTs using Sentaurus TCAD. Traps, inherently unavoidable in semiconductors, can be strategically introduced to engineer specific energy levels that establish competitive dyn...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2025-07-01
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| Series: | Photonics |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2304-6732/12/7/719 |
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| Summary: | This study systematically investigates the effects of trap concentration on self-heating and terahertz (THz) responses in GaN HEMTs using Sentaurus TCAD. Traps, inherently unavoidable in semiconductors, can be strategically introduced to engineer specific energy levels that establish competitive dynamics between the electron momentum relaxation time and the carrier lifetime. A simulation-based exploration of this mechanism provides significant scientific value for enhancing device performance through self-heating mitigation and THz response optimization. An AlGaN/GaN heterojunction HEMT model was established, with trap concentrations ranging from 0 to <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>5</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>17</mn></mrow></msup><mo> </mo><msup><mrow><mi mathvariant="normal">c</mi><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula>. The analysis reveals that traps significantly enhance channel current (achieving 3× gain at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>×</mo><mn>1</mn><msup><mrow><mn>0</mn></mrow><mrow><mn>17</mn></mrow></msup><mo> </mo><msup><mrow><mi mathvariant="normal">c</mi><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula>) via new energy levels that prolong carrier lifetime. However, elevated trap concentrations (><inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>16</mn></mrow></msup><mo> </mo><msup><mrow><mi mathvariant="normal">c</mi><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula>) exacerbate self-heating-induced current collapse, reducing the min-to-max current ratio to 0.9158. In THz response characterization, devices exhibit a distinct DC component (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">U</mi></mrow><mrow><mi mathvariant="normal">d</mi><mi mathvariant="normal">c</mi></mrow></msub></mrow></semantics></math></inline-formula>) under non-resonant detection (<inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mi mathvariant="sans-serif">ω</mi><mi mathvariant="sans-serif">τ</mi><mo>≪</mo><mn>1</mn></mrow></semantics></math></inline-formula>). At a trap concentration of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>1</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>15</mn></mrow></msup><mo> </mo><msup><mrow><mi mathvariant="normal">c</mi><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula>, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">U</mi></mrow><mrow><mi mathvariant="normal">d</mi><mi mathvariant="normal">c</mi></mrow></msub></mrow></semantics></math></inline-formula> peaks at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>0.12</mn><mo> </mo><mi mathvariant="normal">V</mi></mrow></semantics></math></inline-formula> when <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">V</mi></mrow><mrow><mi mathvariant="normal">g</mi></mrow></msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">C</mi><mo>=</mo><mo>−</mo><mn>7.8</mn><mo> </mo><mi mathvariant="normal">V</mi></mrow></semantics></math></inline-formula>. Compared to trap-free devices, a maximum response attenuation of 64.89% occurs at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">V</mi></mrow><mrow><mi mathvariant="normal">g</mi></mrow></msub><mi mathvariant="normal">D</mi><mi mathvariant="normal">C</mi><mo>=</mo><mo>−</mo><mn>4.9</mn><mo> </mo><mi mathvariant="normal">V</mi></mrow></semantics></math></inline-formula>. Furthermore, <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><msub><mrow><mi mathvariant="normal">U</mi></mrow><mrow><mi mathvariant="normal">d</mi><mi mathvariant="normal">c</mi></mrow></msub></mrow></semantics></math></inline-formula> demonstrates non-monotonic behavior with concentration, showing local maxima at <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>4</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>15</mn></mrow></msup><mo> </mo><msup><mrow><mi mathvariant="normal">c</mi><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula> and <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>7</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>15</mn></mrow></msup><mo> </mo><msup><mrow><mi mathvariant="normal">c</mi><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula>, attributed to plasma wave damping and temperature-gradient-induced electric field variations. This research establishes trap engineering guidelines for GaN HEMTs: a concentration of <inline-formula><math xmlns="http://www.w3.org/1998/Math/MathML" display="inline"><semantics><mrow><mn>4</mn><mo>×</mo><msup><mrow><mn>10</mn></mrow><mrow><mn>15</mn></mrow></msup><mo> </mo><msup><mrow><mi mathvariant="normal">c</mi><mi mathvariant="normal">m</mi></mrow><mrow><mo>−</mo><mn>3</mn></mrow></msup></mrow></semantics></math></inline-formula> optimally enhances conductivity while minimizing adverse impacts on both self-heating and the THz response, making it particularly suitable for high-sensitivity terahertz detectors. |
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| ISSN: | 2304-6732 |