The photoluminescence（PL） and electrical properties of Al GaN/GaN high electron mobility transistors（HEMTs） with different Fe doping concentrations in the GaN buffer layers were studied. It was found that, at low ...The photoluminescence（PL） and electrical properties of Al GaN/GaN high electron mobility transistors（HEMTs） with different Fe doping concentrations in the GaN buffer layers were studied. It was found that, at low Fe doping concentrations,the introduction of Fe atoms can result in a downward shift of the Fermi level in the GaN buffer layer, since the Fe atoms substitute Ga and introduce an FeGa^3＋/2＋ acceptor level. This results in a decrease in the yellow luminescence（YL） emission intensity accompanied by the appearance of an infrared（IR） emission, and a decrease in the off-state buffer leakage current（BLC）. However, a further increase in the Fe doping concentration will conversely result in the upward shift of the Fermi level due to the incorporation of O donors under the large flow rate of the Fe source. This results in an increased YL emission intensity accompanied by a decrease in the IR emission intensity, and an increase in the BLC. The intrinsic relationship between the PL and BLC characteristics is expected to provide a simple and effective method to understand the variation of the electrical characteristic in the modulation Fe-doped HEMTs by optical measurements.展开更多
High-performance low-leakage-current A1GaN/GaN high electron mobility transistors （HEMTs） on silicon （111） sub- strates grown by metal organic chemical vapor deposition （MOCVD） with a novel partially Magnesium ...High-performance low-leakage-current A1GaN/GaN high electron mobility transistors （HEMTs） on silicon （111） sub- strates grown by metal organic chemical vapor deposition （MOCVD） with a novel partially Magnesium （Mg）-doped GaN buffer scheme have been fabricated successfully. The growth and DC results were compared between Mg-doped GaN buffer layer and a unintentionally onμe. A 1μ m gate-length transistor with Mg-doped buffer layer exhibited an OFF-state drain leakage current of 8.3 × 10-8 A/mm, to our best knowledge, which is the lowest value reported for MOCVD-grown A1GaN/GaN HEMTs on Si featuring the same dimension and structure. The RF characteristics of 0.25-μ m gate length T-shaped gate HEMTs were also investigated.展开更多
The transport mechanism of reverse surface leakage current in the AlGaN/GaN high-electron mobility transistor（HEMT） becomes one of the most important reliability issues with the downscaling of feature size.In this p...The transport mechanism of reverse surface leakage current in the AlGaN/GaN high-electron mobility transistor（HEMT） becomes one of the most important reliability issues with the downscaling of feature size.In this paper,the research results show that the reverse surface leakage current in AlGaN/GaN HEMT with SiN passivation increases with the enhancement of temperature in the range from 298 K to 423 K.Three possible transport mechanisms are proposed and examined to explain the generation of reverse surface leakage current.By comparing the experimental data with the numerical transport models,it is found that neither Fowler-Nordheim tunneling nor Frenkel-Poole emission can describe the transport of reverse surface leakage current.However,good agreement is found between the experimental data and the two-dimensional variable range hopping（2D-VRH） model.Therefore,it is concluded that the reverse surface leakage current is dominated by the electron hopping through the surface states at the barrier layer.Moreover,the activation energy of surface leakage current is extracted,which is around 0.083 eV.Finally,the SiN passivated HEMT with a high Al composition and a thin AlGaN barrier layer is also studied.It is observed that 2D-VRH still dominates the reverse surface leakage current and the activation energy is around 0.10 eV,which demonstrates that the alteration of the AlGaN barrier layer does not affect the transport mechanism of reverse surface leakage current in this paper.展开更多
We demonstrate a novel Si-rich SiN bilayer passivation technology for AlGaN/GaN high electron mobility transistors(HEMTs)with thin-barrier to minimize surface leakage current to enhance the breakdown voltage.The bilay...We demonstrate a novel Si-rich SiN bilayer passivation technology for AlGaN/GaN high electron mobility transistors(HEMTs)with thin-barrier to minimize surface leakage current to enhance the breakdown voltage.The bilayer SiN with 20-nm Si-rich SiN and 100-nm Si_(3)N_(4) was deposited by plasma-enhanced chemical vapor deposition(PECVD)after removing 20-nm SiO_(2)pre-deposition layer.Compared to traditional Si_(3)N_(4) passivation for thin-barrier AlGaN/GaN HEMTs,Si-rich SiN bilayer passivation can suppress the current collapse ratio from 18.54%to 8.40%.However,Si-rich bilayer passivation leads to a severer surface leakage current,so that it has a low breakdown voltage.The 20-nm SiO_(2)pre-deposition layer can protect the surface of HEMTs in fabrication process and decrease Ga–O bonds,resulting in a lower surface leakage current.In contrast to passivating Si-rich SiN directly,devices with the novel Si-rich SiN bilayer passivation increase the breakdown voltage from 29 V to 85 V.Radio frequency(RF)small-signal characteristics show that HEMTs with the novel bilayer SiN passivation leads to f_(T)/f_(max) of 68 GHz/102 GHz.At 30 GHz and V_(DS)=20 V,devices achieve a maximum P_(out) of 5.2 W/mm and a peak power-added efficiency(PAE)of 42.2%.These results indicate that HEMTs with the novel bilayer SiN passivation can have potential applications in the millimeter-wave range.展开更多
The gate forward leakage current in AlGaN/GaN high electron mobility transistors （HEMTs） is investigated. It is shown that the current which originated from the forward biased Schottky-gate contributed to the gate f...The gate forward leakage current in AlGaN/GaN high electron mobility transistors （HEMTs） is investigated. It is shown that the current which originated from the forward biased Schottky-gate contributed to the gate forward leakage current. Therefore, a fluorine-plasma surface treatment is presented to induce the negative ions into the AlGaN layer which results in a higher metal-semiconductor barrier. Consequently, the gate forward leak- age current shrinks. Experimental results confirm that the gate forward leakage current is decreased by one order magnitude lower than that of HEMT device without plasma treatment. In addition, the DC characteristics of the HEMT device with plasma treatment have been studied.展开更多
基金Project supported by the Major Research Plan of the National Natural Science Foundation of China(Grant No.91433112)the National Natural Science Foundation of China(Grant No.51672163)the Key Laboratory of Functional Crystal Materials and Device(Shandong University,Ministry of Education),China(Grant No.JG1401)
文摘The photoluminescence（PL） and electrical properties of Al GaN/GaN high electron mobility transistors（HEMTs） with different Fe doping concentrations in the GaN buffer layers were studied. It was found that, at low Fe doping concentrations,the introduction of Fe atoms can result in a downward shift of the Fermi level in the GaN buffer layer, since the Fe atoms substitute Ga and introduce an FeGa^3＋/2＋ acceptor level. This results in a decrease in the yellow luminescence（YL） emission intensity accompanied by the appearance of an infrared（IR） emission, and a decrease in the off-state buffer leakage current（BLC）. However, a further increase in the Fe doping concentration will conversely result in the upward shift of the Fermi level due to the incorporation of O donors under the large flow rate of the Fe source. This results in an increased YL emission intensity accompanied by a decrease in the IR emission intensity, and an increase in the BLC. The intrinsic relationship between the PL and BLC characteristics is expected to provide a simple and effective method to understand the variation of the electrical characteristic in the modulation Fe-doped HEMTs by optical measurements.
文摘High-performance low-leakage-current A1GaN/GaN high electron mobility transistors （HEMTs） on silicon （111） sub- strates grown by metal organic chemical vapor deposition （MOCVD） with a novel partially Magnesium （Mg）-doped GaN buffer scheme have been fabricated successfully. The growth and DC results were compared between Mg-doped GaN buffer layer and a unintentionally onμe. A 1μ m gate-length transistor with Mg-doped buffer layer exhibited an OFF-state drain leakage current of 8.3 × 10-8 A/mm, to our best knowledge, which is the lowest value reported for MOCVD-grown A1GaN/GaN HEMTs on Si featuring the same dimension and structure. The RF characteristics of 0.25-μ m gate length T-shaped gate HEMTs were also investigated.
基金supported by the National Natural Science Foundation of China(Grant Nos.61334002,61106106,and 61474091)the Opening Project of Science and Technology on Reliability Physics and Application Technology of Electronic Component Laboratory,China(Grant No.ZHD201206)+3 种基金the New Experiment Development Funds for Xidian University,China(Grant No.SY1213)the 111 Project,China(Grant No.B12026)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry,Chinathe Fundamental Research Funds for the Central Universities,China(Grant No.K5051325002)
文摘The transport mechanism of reverse surface leakage current in the AlGaN/GaN high-electron mobility transistor（HEMT） becomes one of the most important reliability issues with the downscaling of feature size.In this paper,the research results show that the reverse surface leakage current in AlGaN/GaN HEMT with SiN passivation increases with the enhancement of temperature in the range from 298 K to 423 K.Three possible transport mechanisms are proposed and examined to explain the generation of reverse surface leakage current.By comparing the experimental data with the numerical transport models,it is found that neither Fowler-Nordheim tunneling nor Frenkel-Poole emission can describe the transport of reverse surface leakage current.However,good agreement is found between the experimental data and the two-dimensional variable range hopping（2D-VRH） model.Therefore,it is concluded that the reverse surface leakage current is dominated by the electron hopping through the surface states at the barrier layer.Moreover,the activation energy of surface leakage current is extracted,which is around 0.083 eV.Finally,the SiN passivated HEMT with a high Al composition and a thin AlGaN barrier layer is also studied.It is observed that 2D-VRH still dominates the reverse surface leakage current and the activation energy is around 0.10 eV,which demonstrates that the alteration of the AlGaN barrier layer does not affect the transport mechanism of reverse surface leakage current in this paper.
基金Project supported by the National Key Research and Development Program of China(Grant No.2020YFB1804902)the National Natural Science Foundation of China(Grant Nos.61904135,62090014,and 11690042)+4 种基金the Fundamental Research Funds for the Central Universities,the Innovation Fund of Xidian University(Grant No.YJS2213)the China Postdoctoral Science Foundation(Grant Nos.2018M640957 and BX20200262)the Key Research and Development Program of Guangzhou(Grant No.202103020002)Wuhu and Xidian University Special Fund for Industry–University-Research Cooperation(Grant No.XWYCXY-012021014HT)the Fundamental Research Funds for the Central Universities,China(Grant No.XJS221110)。
文摘We demonstrate a novel Si-rich SiN bilayer passivation technology for AlGaN/GaN high electron mobility transistors(HEMTs)with thin-barrier to minimize surface leakage current to enhance the breakdown voltage.The bilayer SiN with 20-nm Si-rich SiN and 100-nm Si_(3)N_(4) was deposited by plasma-enhanced chemical vapor deposition(PECVD)after removing 20-nm SiO_(2)pre-deposition layer.Compared to traditional Si_(3)N_(4) passivation for thin-barrier AlGaN/GaN HEMTs,Si-rich SiN bilayer passivation can suppress the current collapse ratio from 18.54%to 8.40%.However,Si-rich bilayer passivation leads to a severer surface leakage current,so that it has a low breakdown voltage.The 20-nm SiO_(2)pre-deposition layer can protect the surface of HEMTs in fabrication process and decrease Ga–O bonds,resulting in a lower surface leakage current.In contrast to passivating Si-rich SiN directly,devices with the novel Si-rich SiN bilayer passivation increase the breakdown voltage from 29 V to 85 V.Radio frequency(RF)small-signal characteristics show that HEMTs with the novel bilayer SiN passivation leads to f_(T)/f_(max) of 68 GHz/102 GHz.At 30 GHz and V_(DS)=20 V,devices achieve a maximum P_(out) of 5.2 W/mm and a peak power-added efficiency(PAE)of 42.2%.These results indicate that HEMTs with the novel bilayer SiN passivation can have potential applications in the millimeter-wave range.
基金Project supported by the National Natural Science Foundation of China(No.60906037)the Research Fund for the Doctoral Program of Higher Education of China(No.20090185120021)
文摘The gate forward leakage current in AlGaN/GaN high electron mobility transistors （HEMTs） is investigated. It is shown that the current which originated from the forward biased Schottky-gate contributed to the gate forward leakage current. Therefore, a fluorine-plasma surface treatment is presented to induce the negative ions into the AlGaN layer which results in a higher metal-semiconductor barrier. Consequently, the gate forward leak- age current shrinks. Experimental results confirm that the gate forward leakage current is decreased by one order magnitude lower than that of HEMT device without plasma treatment. In addition, the DC characteristics of the HEMT device with plasma treatment have been studied.
