Comparison of GaN/AlGaN/AlN/GaN HEMTs Grown on Sapphire with Fe-Modulation-Doped and Unintentionally Doped GaN Buffer: Material Growth and Device Fabrication
Jia-Min Gong1, Quan Wang1,2**, Jun-Da Yan2, Feng-Qi Liu2, Chun Feng2, Xiao-Liang Wang2, Zhan-Guo Wang2
1School of Electronic Engineering, Xi'an University of Posts and Telecommunications, Xi'an 710121 bKey Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083
Abstract：AlGaN/GaN high electron mobility transistors (HEMTs) grown on Fe-modulation-doped (MD) and unintentionally doped (UID) GaN buffer layers are investigated and compared. Highly resistive GaN buffers (10$^{9}$ $\Omega$$\cdot$cm) are induced by individual mechanisms for the electron traps' formation: the Fe MD buffer (sample A) and the UID buffer with high density of edge-type dislocations ($7.24\times10^{9}$ cm$^{-2}$, sample B). The 300 K Hall test indicates that the mobility of sample A with Fe doping (2503 cm$^{2}$V$^{-1}$s$^{-1}$) is much higher than sample B (1926 cm$^{2}$V$^{-1}$s$^{-1})$ due to the decreased scattering effect on the two-dimensional electron gas. HEMT devices are fabricated on the two samples and pulsed $I$–$V$ measurements are conducted. Device A shows better gate pinch-off characteristics and a higher threshold voltage ($-$2.63 V) compared with device B ($-$3.71 V). Lower gate leakage current $|I_{\rm GS}|$ of device A ($3.32\times10^{-7}$ A) is present compared with that of device B ($8.29\times10^{-7}$ A). When the off-state quiescent points $Q_{2}$ ($V_{\rm GQ2}=-8$ V, $V_{\rm DQ2}=0$ V) are on, $V_{\rm th}$ hardly shifts for device A while device B shows +0.21 V positive threshold voltage shift, resulting from the existence of electron traps associated with the dislocations in the UID-GaN buffer layer under the gate. Under pulsed $I$–$V$ and transconductance $G_{\rm m}$–$V_{\rm GS}$ measurement, the device with the Fe MD-doped buffer shows more potential in improving reliability upon off-state stress.
. [J]. 中国物理快报, 2016, 33(11): 117303-117303.
Jia-Min Gong, Quan Wang, Jun-Da Yan, Feng-Qi Liu, Chun Feng, Xiao-Liang Wang, Zhan-Guo Wang. Comparison of GaN/AlGaN/AlN/GaN HEMTs Grown on Sapphire with Fe-Modulation-Doped and Unintentionally Doped GaN Buffer: Material Growth and Device Fabrication. Chin. Phys. Lett., 2016, 33(11): 117303-117303.
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2016, Vol. 33 
