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Kaper V.S. Tilak V. Hyungtak Kim Vertiatchikh A.V. Thompson R.M. Prunty T.R. Eastman L.F. Shealy J.R. 《Solid-State Circuits, IEEE Journal of》2003,38(9):1457-1461
A monolithic X-band oscillator based on an AlGaN/GaN high electron mobility transistor (HEMT) has been designed, fabricated, and characterized. A common-gate HEMT with 1.5 mm of gate width in conjunction with inductive feedback is used to generate negative resistance. A high Q resonator is implemented with a short-circuit low-loss coplanar waveguide transmission line. The oscillator delivers 1.7 W at 9.556 GHz into 50-/spl Omega/ load when biased at V/sub ds/=30 V and V/sub gs/=-5 V, with dc-to-RF efficiency of 16%. Phase noise was estimated to be -87 dBc/Hz at 100-kHz offset. Low-frequency noise, pushing and pulling figures, and time-domain characterization have been performed. Experimental results show great promise for AlGaN/GaN HEMT MMIC technology to be used in future high-power microwave source applications. 相似文献
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Correlation of device performance and defects in AlGaN/GaN high-electron mobility transistors 总被引:2,自引:0,他引:2
A. P. Zhang L. B. Rowland E. B. Kaminsky V. Tilak J. C. Grande J. Teetsov A. Vertiatchikh L. F. Eastman 《Journal of Electronic Materials》2003,32(5):388-394
Device performance and defects in AlGaN/GaN high-electron mobility transistors (HEMTs) have been correlated. Surface depressions
and threading dislocations, revealed by optical-defect mapping and atomic force microscopy (AFM), compromised the effectiveness
of the SiNx surface-passivation effect as evidenced by the gate-lag measurements. The residual carriers in the GaN-buffer layer observed
from the capacitance-voltage depth profile have been attributed to the point defects and threading dislocations either acting
as donors or causing local charge accumulations. Deep-level transient-spectroscopy measurements showed the existence of several
traps corresponding to surface states and bulk-dislocation defects. The formation of electron-accumulation regions on the
surface or (and) in the GaN-buffer layer was confirmed by currentvoltage measurements. This second, virtual gate formed by
electron accumulations can deplete the channel and cause a large-signal gain collapse leading to degraded output power. A
good correlation was established between the device performance and defects in AlGaN/GaN HEMT structure. 相似文献
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Influence of 4H-SiC semi-insulating substrate purity on SiC metal-semiconductor field-effect transistor performance 总被引:1,自引:0,他引:1
A. P. Zhang L. B. Rowland E. B. Kaminsky J. B. Tucker R. A. Beaupre J. W. Kretchmer J. L. Garrett A. Vertiatchikh G. Koley H. Y. Cha A. F. Allen J. Cook J. Foppes B. J. Edward 《Journal of Electronic Materials》2003,32(5):437-443
The performances of silicon carbide (SiC) metal-semiconductor field-effect transistors (MESFETs) fabricated on conventional
V-doped semi-insulating substrates and new V-free semi-insulating substrates have been compared. The V-free 4H-SiC substrates
were confirmed by secondary ion mass spectrometry (SIMS). X-ray topography revealed significantly fewer micropipes and low-angle
boundaries in V-free semi-insulating substrates than in conventional V-compensated substrates. Deep-level transient spectroscopy
(DLTS) indicated that the spectra signals observed in conventional V-doped substrates were either reduced or disappeared in
V-free substrates. The intrinsic deep levels in V-free substrates to make semi-insulating properties were also observed in
DLTS spectra. Under various DC and RF stresses, SiC MESFETs fabricated on new V-free semi-insulating substrates showed superior
device performance and stability. 相似文献
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The effect of SiN passivation of the surface of AlGaN/GaN transistors is reported. Current deep level transient spectroscopy (DLTS) measurements were performed on the device before and after the passivation by a SiN film. The DLTS spectra from these measurements showed the existence of the same electron trap on the surface of the device. The DLTS spectrum obtained from the measurement of the passivated device showed a significantly lower peak for this trap. The discrepancy in the DLTS peak amplitude is explained by the effect of the passivation on the surface traps and underlines the surface nature of the major defect noticed in the device 相似文献
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We report on the effect of Si/sub 3/N/sub 4/ passivation of the surface of AlGaN/GaN transistors on low-frequency noise performance. Low-frequency noise measurements were performed on the device before and after the passivation by a Si/sub 3/N/sub 4/ film. A lower level of the low-frequency noise was observed from the device after the passivation. The passivation layer improved high-frequency, large-signal device performance, but introduced parasitic leakage current from the gate. A lower level of flicker noise is explained by the fact that noise is mostly originated from the fluctuation of sheet charge and mobility in the ungated region of the device due to the defects on the surface and in the barrier of the unpassivated device. Passivation eliminates part of the defects and higher leakage current increases the number of electrons on the surface and in the vicinity of the barrier defects, lowering the contribution to the low-frequency noise according to Hooge's law. 相似文献
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