scholarly journals Investigation of AlGaN/GaN HFET and VO2 Thin Film Based Deflection Transducers Embedded in GaN Microcantilevers

Micromachines ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 875
Author(s):  
Ferhat Bayram ◽  
Durga Gajula ◽  
Digangana Khan ◽  
Goutam Koley
Keyword(s):  
Thin Film ◽  
Field Effect Transistors ◽  
Large Change ◽  
Drain Current ◽  
Gate Bias ◽  
Operation Temperature ◽  
Source Resistance ◽  
Gan Hfet ◽  
Vo2 Thin Films ◽  
Nonlinear Behaviors

The static and dynamic deflection transducing performances of piezotransistive AlGaN/GaN heterojunction field effect transistors (HFET) and piezoresistive VO2 thin films, fabricated on GaN microcantilevers of similar dimensions, were investigated. Deflection sensitivities were tuned with the gate bias and operating temperature for embedded AlGaN/GaN HFET and VO2 thin film transducers, respectively. The GaN microcantilevers were excited with a piezoactuator in their linear and nonlinear oscillation regions of the fundamental oscillatory mode. In the linear regime, the maximum deflection sensitivity of piezotransistive AlGaN/GaN HFET reached up to a 0.5% change in applied drain voltage, while the responsivity of the piezoresistive VO2 thin film based deflection transducer reached a maximum value of 0.36% change in applied drain current. The effects of the gate bias and the operation temperature on nonlinear behaviors of the microcantilevers were also experimentally examined. Static deflection sensitivity measurements demonstrated a large change of 16% in drain-source resistance of the AlGaN/GaN HFET, and a similarly high 11% change in drain-source resistance in the VO2 thin film, corresponding to a 10 μm downward step bending of the cantilever free end.

RECENT PROGRESS ON GaN-BASED ELECTRON DEVICES

2006 ◽  
Vol 16 (02) ◽  
pp. 469-477
Author(s):  
Yasuhiro Uemoto ◽  
Yutaka Hirose ◽  
Tomohiro Murata ◽  
Hidetoshi Ishida ◽  
Masahiro Hikita ◽  
...  
Keyword(s):  
Noise Figure ◽  
Field Effect Transistors ◽  
Drain Current ◽  
Low Noise ◽  
60 Ghz ◽  
Si Doping ◽  
Power Handling Capability ◽  
Source Resistance ◽  
State Breakdown ◽  
A Current

We present results of some novel AlGaN/GaN heterojunction field-effect transistors (HFETs) specifically developed for RF front-end and power applications. To reduce the parasitic resistance, two unique techniques: selective Si doping into contact area and a superlattice (SL) cap structure, are developed. With the selective Si doping method, a transistor with an on-state resistance as low as 1.86 Ω·mm and a Tx/Rx switch IC with very low insertion loss (0.26 dB) and very high power handling capability (P1dB over 40 dBm) were obtained. With the SL cap HFETs, an ultra low source resistance of 0.4 Ω·mm was achieved and excellent DC and RF performances were demonstrated. The typical characteristics of these HFETs are: maximum transconductance of over 400 mS/mm, maximum drain current of 1.2 A/mm, cut-off frequency of 60 GHz, maximum oscillation frequency of 140 GHz, and a very low noise figure of 0.7 dB with 15 dB gain at 12 GHz. For power applications, in order to significantly reduce fabrication cost, we fabricated the AlGaN/GaN HFET on a conductive Si substrate with a source-via grounding (SVG) structure. The device has a very low on-state sheet resistance of 1.9 mΩ·cm2, a high off-state breakdown voltage of 350 V, and a current handling capability of 150 A. In addition, a sub-nano second switching response with t r of 98 ps and t f of 96 ps with a current density as high as 2.0 kA/cm2 is demonstrated for the first time.

scholarly journals Preliminary Evaluation of Pentacene Field Effect Transistors with Polymer Gate Electret as Ionizing Radiation Dosimeters

2021 ◽  
Vol 11 (23) ◽  
pp. 11368
Author(s):  
Irina Valitova ◽  
Alexandria Mitchell ◽  
Michael A. Hupman ◽  
Ian G. Hill ◽  
Alasdair Syme
Keyword(s):  
Thin Film ◽  
Dose Rate ◽  
Real Time ◽  
Field Effect Transistors ◽  
Drain Current ◽  
Radiation Detectors ◽  
Organic Thin Film ◽  
Effective Response ◽  
Treatment Unit ◽  
Sensing Applications

Interest in the use of organic electronic devices in radiation sensing applications has grown in recent years. The numerous device configurations (e.g., diodes, thin film transistors) and potential for improved tissue equivalence compared to their silicon-based analogues make them attractive candidates for various radiation dosimetry measurements. In this work, a variation of the organic thin film transistor (OTFT) is studied, in which a polymer electret is added. An OTFT electret design can be used in either a wired or wireless configuration for in vivo dosimetry with the possibility of real-time detection. The linearity, reproducibility, and dependence on energy of these devices were measured through exposure to 100 kVp photons from an orthovoltage treatment unit (Xstrahl 300) and 6 MV photons from a Varian TrueBeam medical linear accelerator. Prior to irradiation, all transistors were programmed with a −80 V bias applied to the Gate electrode (Vg) for 3 s. In the wireless configuration, after each delivered dose, the transfer characteristic was scanned to readout the amount of erased charges by monitoring the drain current change. When the programmed charge was sufficiently depleted by radiation, transistors were reprogrammed for repeated use. The real-time readout in a wired configuration was performed by measuring the drain current with Vg = −15 V; Vd = −15 V. The 6 MV photon beam was turned on and off at different dose rates of 600, 400, 300, 200, and 60 cGy/min to quantify the sensitivity of the device to changes in dose rate. The wireless transistors showed a linear increase in current with increasing dose. The sensitivities for different energies were 60 ± 5 nA/Gy at 6 MV at a dose rate of 600 cGy/min and 80 ± 10 nA/Gy at 100 kVp at a dose rate of 200 cGy/min. The sensitivity of detectors tested in a wired configuration at Vd = −15 V; Vg = −15 V was 8.1 nA/s at a dose rate of 600 cGy/min. The principle of pentacene OTFTs with polymer electret as radiation detectors was demonstrated. Devices had excellent linearity, reproducibility, and were able to be reprogrammed for multiple uses as wireless detectors. The wired transistors demonstrated an effective response as real-time detectors.

The Impact of the Extrinsic Device on HFET Performance

1991 ◽  
Vol 240 ◽  
Author(s):  
David R. Greenberg ◽  
Jesús A. Del Alamo
Keyword(s):  
Field Effect Transistors ◽  
Drain Current ◽  
Metal Insulator ◽  
Figures Of Merit ◽  
Velocity Saturation ◽  
Heterostructure Field Effect Transistors ◽  
Source Resistance ◽  
Carrier Velocity ◽  
The Impact ◽  
Ultimate Limit

ABSTRACTThe extrinsic device is known to degrade the performance of heterostructure field-effect transistors (HFET's) through the introduction of a parasitic source resistance (Rs). To date, however, there has been no recognition of the fact that carrier velocity saturation (vsat) can occur in both the extrinsic source and drain, setting the ultimate limit on maximum drain current (I,D,max) and on the useful VGS swing in HFET's. In this study, we demonstrate the mechanisms through which vsat in the extrinsic device limits device performance, using AlGaAs/n+-InGaAs Metal-Insulator-Doped-channel FET's (MIDFET's) as a vehicle. These devices show that gm falls at a lower VGSthan does fT, by as much as 1 V. This reveals that there are two mechanisms at work. The approach of vsat in the extrinsic source first causes the small-signal source resistance (Ts)to rise rapidly, leading gm to decline but leaving fT unaffected. As the carrier velocity in the extrinsic device approaches Vsat more closely, there is an actual decline of the carrier velocity in the intrinsic device. This process degrades velocity-related figures of merit such as and fT.

Long Time-Constant Trap Effects in Nitride Heterostructure Field Effect Transistors

2000 ◽  
Vol 622 ◽  
Author(s):  
Xiaozhong Dang ◽  
Peter M. Asbeck ◽  
Edward T. Yu ◽  
Karim S. Boutros ◽  
Joan M. Redwing
Keyword(s):  
Field Effect Transistors ◽  
Current Response ◽  
Gate Bias ◽  
Current Collapse ◽  
Heterostructure Field Effect Transistors ◽  
Long Time ◽  
Gan Hfet ◽  
Koh Etching ◽  
Or Gate ◽  
Drain Lag

ABSTRACTCurrent collapse effects in an Al0.25Ga0.75N/GaN HFET have been investigated under pulsed bias conditions, and a detailed investigation of current responses to changes in drain or gate bias voltage (drain-lag and gate-lag, respectively) has been performed. Three components of transient current response to changes in drain and gate bias voltages are distinguished. Surface treatment using KOH etching and the influence of pulsed bias conditions on threshold voltage are investigated to explore the origins of traps associated with each current transient component.

Dielectric Effects in Laser-Crystallised Polycrystalline Silicon Thin Film Transistors

1995 ◽  
Vol 377 ◽  
Author(s):  
G. H. Masterton ◽  
R. A. G. Gibson ◽  
M. Hack
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Polycrystalline Silicon ◽  
Gate Dielectric ◽  
Drain Current ◽  
Generation Process ◽  
Gate Bias ◽  
Silicon Thin Film ◽  
Transient Behaviour ◽  
Current Decay

ABSTRACTWe present experimental results on the transient response of the source-drain current of laser crystallised polycrystalline silicon (poly-Si) thin film transistors (TFTs) over many orders of magnitude in time after the application of a voltage pulse to the gate electrode. This work follows on from similar measurements performed on amorphous silicon (a-Si) TFTs. Results showed a definite change in transient behaviour dependent on the magnitude of the gate bias. At a gate voltage of 5V there was an initial decay then a marked increase in the source-drain current beyond 1000 seconds. This variation of transient behaviour with gate bias was not seen in the a-Si case. For poly-Si the transient behaviour could not be split into different regimes in time (beyond the carrier transit time) whereas for a-Si TFTs the source-drain current showed a logarithmic decay at room temperature up to 100 seconds followed by a power law decay beyond 100 seconds. Our results indicate perhaps that only one mechanism exists for the observed transient decay of current, unlike the a-Si case. Measurements carried out at elevated temperature showed the current decay was independent of temperature indicating that the transient decay may be caused by charge injection via a tunnelling process into interface states, gate dielectric or passivation dielectric. Finally by carrying out measurements on TFTs after moderate positive voltage stressing and on TFTs with specially fabricated gate and passivation dielectrics it has been established that the transient decay is dielectric related and not a defect generation process.

1360 V, 5.0 mΩcm2 Double-Implanted MOSFETs Fabricated on 4H-SiC(000-1)

2010 ◽  
Vol 645-648 ◽  
pp. 987-990 ◽  
Author(s):  
Hiroshi Kono ◽  
Takuma Suzuki ◽  
Makoto Mizukami ◽  
Chiharu Ota ◽  
Shinsuke Harada ◽  
...  
Keyword(s):  
Silicon Carbide ◽  
Field Effect ◽  
Room Temperature ◽  
Field Effect Transistors ◽  
Drain Current ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
Gate Bias ◽  
Drain Voltage ◽  
Blocking Voltage

Silicon carbide Double-Implanted Metal-Oxide-Semiconductor Field-Effect Transistors (DIMOSFETs) were fabricated on 4H-SiC (000-1) carbon face. The DIMOSFETs were characterized from room temperature to 250°C. At room temperature, they showed a specific on-resistance of 4.9 mΩcm2 at a gate bias of 20 V and a drain voltage of 1.0 V. The specific on-resistance taken at a drain current (Id) of 260 A/cm2 was 5.0 mΩcm2. The blocking voltage of this device was higher than 1360 V at room temperature. At 250°C, the specific on-resistance increased from 5.0 mΩcm2 to 12.5 mΩcm2 and the threshold voltage determined at Id = 26 mA/cm2 decreased from 5.5 V to 4.3 V.

Metal-Semiconductor-Insulator-Metal Structure Field-Effect Transistors Based on Zinc Oxides and Doped Ferroelectric Thin Films

2014 ◽  
Vol 1633 ◽  
pp. 131-137 ◽  
Author(s):  
Ze Jia ◽  
Jianlong Xu ◽  
Xiao Wu ◽  
Mingming Zhang ◽  
Naiwen Zhang ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Zinc Oxide ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Sol Gel ◽  
Drain Current ◽  
Metal Structure ◽  
Ferroelectric Materials ◽  
Ferroelectric Thin Films

ABSTRACTDifferent ferroelectric thin films and their related Metal-Semiconductor-Insulator-Metal (MSIM) structures include zinc oxide (ZnO) are studied, which can be utilized in back-gated ferroelectric field-effect transistors (FETs). The most ideal zinc oxide (ZnO) thin film prepared by sol-gel method are obtained under the pyrolysis temperature of 400°C and the annealing temperature of 600°C. The asymmetric or symmetric current-voltage characteristics of the heterostructures with ZnO are exhibited depending on different ferroelectric materials in them. The curves of drain current versus gate voltage for MSIM-structure FETs are investigated, in which obvious counterclockwise loops and a drain current switching ratio up to two orders of magnitude ate observed due to the modulation effect of remnant polarization on the channel resistance. The results also indicate the positive influences of impurity atom substitution in bismuth ferrite thin film for the MSIM-structure FETs.

Effect of Illumination on Organic Polymer Thin-Film Transistors

2003 ◽  
Vol 771 ◽  
Author(s):  
Michael C. Hamilton ◽  
Sandrine Martin ◽  
Jerzy Kanicki
Keyword(s):  
Thin Film ◽  
Thin Film Transistors ◽  
Drain Current ◽  
Charge Carriers ◽  
Electrical Performance ◽  
Organic Polymer ◽  
Light Illumination ◽  
Polymer Thin Film ◽  
Channel Region ◽  
White Light Illumination

AbstractWe have investigated the effects of white-light illumination on the electrical performance of organic polymer thin-film transistors (OP-TFTs). The OFF-state drain current is significantly increased, while the drain current in the strong accumulation regime is relatively unaffected. At the same time, the threshold voltage is decreased and the subthreshold slope is increased, while the field-effect mobility of the charge carriers is not affected. The observed effects are explained in terms of the photogeneration of free charge carriers in the channel region due to the absorbed photons.

Wide range modulation of synaptic weight in thin-film transistors with hafnium oxide gate insulator and indium-zinc oxide channel layer for artificial synapse application

Nanoscale ◽  
2021 ◽  
Author(s):  
Keonwon Beom ◽  
Jimin Han ◽  
Hyun-Mi Kim ◽  
Tae-Sik Yoon
Keyword(s):  
Thin Film ◽  
Zinc Oxide ◽  
Thin Film Transistors ◽  
Hafnium Oxide ◽  
Synaptic Weight ◽  
Drain Current ◽  
Gate Insulator ◽  
Channel Layer ◽  
Indium Zinc Oxide ◽  
Wide Range

Wide range synaptic weight modulation with a tunable drain current was demonstrated in thin-film transistors (TFTs) with a hafnium oxide (HfO2−x) gate insulator and an indium-zinc oxide (IZO) channel layer...

Development of 1200 V, 3.7 mΩ-cm2 4H-SiC DMOSFETs for Advanced Power Applications

2012 ◽  
Vol 717-720 ◽  
pp. 1059-1064 ◽  
Author(s):  
Sei Hyung Ryu ◽  
Lin Cheng ◽  
Sarit Dhar ◽  
Craig Capell ◽  
Charlotte Jonas ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Room Temperature ◽  
Voltage Drop ◽  
Drain Current ◽  
Subthreshold Swing ◽  
Active Area ◽  
Gate Bias ◽  
Forward Voltage ◽  
Recent Developments ◽  
Forward Voltage Drop

We present our recent developments in 4H-SiC power DMOSFETs. 4H-SiC DMOSFETs with a room temperature specific on-resistance of 3.7 mΩ-cm2 with a gate bias of 20 V, and an avalanche voltage of 1550 V with gate shorted to source, was demonstrated. A threshold voltage of 3.5 V was extracted from the power DMOSFET, and a subthreshold swing of 200 mV/dec was measured. The device was successfully scaled to an active area of 0.4 cm2, and the resulting device showed a drain current of 377 A at a forward voltage drop of 3.8 V at 25oC.

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