Systematic Investigation of 4H-SiC Trench Properties Dependence on Channel Concentration, Crystallographic Plane, and MOS Interface Treatment

2016 ◽  
Vol 858 ◽  
pp. 639-642 ◽  
Author(s):  
Hidenori Kitai ◽  
Tomoaki Hatayama ◽  
Hideto Tamaso ◽  
Shinaya Kyogoku ◽  
Takeyoshi Masuda ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Epitaxial Growth ◽  
Threshold Voltage ◽  
Field Effect ◽  
Systematic Investigation ◽  
Crystallographic Plane ◽  
Field Effect Mobility ◽  
Channel Mobility ◽  
P Type ◽  
Interface Treatment

We have systematically investigated the trench properties of 4H-SiC for p-type channel doping level formed by epitaxial growth, crystallographic plane, and MOS interface treatment. Our results show that the channel mobilities on the (1-100), (11-20), (-1100), and (-1-120) planes gradually decreased in the range from 1 × 1016 to 1 × 1017 cm-3 as the epitaxial channel concentration increased. An inevitable tradeoff existed between channel mobility (field-effect mobility, µFE) and threshold voltage (Vth) in trench MOSFETs. Furthermore, the maximum µFE at a channel concentration of 1 × 1017 cm-3 was 95 cm2·V-1·s-1 on the (11-20) plane with wet + hydrogen (H2) annealing, 83 cm2·V-1·s-1 on the (1-100) plane with wet + H2 annealing and 57 cm2·V-1·s-1 on the (1-100) plane with nitric oxide annealing.

High-Mobility SiC MOSFETs with Alkaline Earth Interface Passivation

2016 ◽  
Vol 858 ◽  
pp. 671-676 ◽  
Author(s):  
Daniel J. Lichtenwalner ◽  
Vipindas Pala ◽  
Brett A. Hull ◽  
Scott Allen ◽  
John W. Palmour
Keyword(s):  
Nitric Oxide ◽  
Field Effect ◽  
Alkaline Earth ◽  
Phonon Scattering ◽  
Breakdown Strength ◽  
Field Effect Transistors ◽  
Oxide Semiconductor ◽  
Field Effect Mobility ◽  
Channel Mobility ◽  
Alkaline Earth Elements

Alkaline earth elements Sr and Ba provide SiO2/SiC interface conditions suitable for obtaining high channel mobility metal-oxide-semiconductor field-effect-transistors (MOSFETs) on the Si-face (0001) of 4H-SiC, without the standard nitric oxide (NO) anneal. The alkaline earth elements Sr and Ba located at/near the SiO2/SiC interface result in field-effect mobility (μFE) values as high as 65 and 110 cm2/V.s, respectively, on 5×1015 cm-3 Al-doped p-type SiC. As the SiC doping increases, peak mobility decreases as expected, but the peak mobility remains higher for Ba interface layer (Ba IL) devices compared to NO annealed devices. The Ba IL MOSFET field-effect mobility decreases as the temperature is increased to 150 °C, as expected when mobility is phonon-scattering-limited, not interface-trap-limited. This is in agreement with measurements of the interface state density (DIT) using the high-low C-V technique, indicating that the Ba IL results in lower DIT than that of samples with nitric oxide passivation. Vertical power MOSFET (DMOSFET) devices (1200V, 15A) fabricated with the Ba IL have a 15% lower on-resistance compared to devices with NO passivation. The DMOSFET devices with a Ba IL maintain a stable threshold voltage under NBTI stress conditions of-15V gate bias stress, at 150 °C for 100hrs, indicating no mobile ions. Secondary-ion mass-spectrometry (SIMS) analysis confirms that the Sr and Ba remain predominantly at the SiO2/SiC interface, even after high temperature oxide annealing, consistent with the observed high channel mobility after these anneals. The alkaline earth elements result in enhanced SiC oxidation rate, and the resulting gate oxide breakdown strength is slightly reduced compared to NO annealed thermal oxides on SiC.

Improved Performance p-type Polymer (P3HT) / n-type Nanotubes (WS2) Electrolyte Gated Thin-Film Transistor

MRS Advances ◽  
2018 ◽  
Vol 3 (27) ◽  
pp. 1525-1533 ◽  
Author(s):  
Eleonora Macchia ◽  
Alla Zak ◽  
Rosaria Anna Picca ◽  
Kyriaki Manoli ◽  
Cinzia Di Franco ◽  
...  
Keyword(s):  
Thin Film ◽  
Threshold Voltage ◽  
Field Effect ◽  
Thin Film Transistor ◽  
Fold Increase ◽  
Field Effect Mobility ◽  
Figures Of Merit ◽  
Electronic Channel ◽  
Improved Performance ◽  
P Type

ABSTRACTThis work decribes the enhancement of the electrical figures of merit of an Electrolyte Gated Thin-Film Transistor (EG-TFT) comprising a nanocomposite of n-type tungsten disulfide (WS2) nanotubes (NTs) dispersed in a regio-regular p-type poly(3-hexylthiophene-2,5-diyl) (P3HT) polymeric matrix. P3HT/WS2 nanocomposites loaded with different concentrations of NTs, serving as EG-TFTs electronic channel materials have been studied and the formulation has been optimized. The resulting EG-TFTs figures of merit (field-effect mobility, threshold voltage and on-off ratio) are compared with those of the device comprising a bare P3HT semiconducting layer. The optimized P3HT/WS2 nanocomposite, comprising a 60% by weight of NTs, results in an improvement of all the elicited figures of merit with a striking ten-fold increase in the field-effect mobility and the on/off ratio along with a sizable enhancement of the in-water operational stability of the device.

Comparison of channel mobility and oxide properties of MOSFET devices on Si-face (0001) and A-face (11-20) 4H-SiC

2014 ◽  
Vol 1693 ◽  
Author(s):  
Daniel J. Lichtenwalner ◽  
Lin Cheng ◽  
Scott Allen ◽  
John W. Palmour ◽  
Aivars Lelis ◽  
...  
Keyword(s):  
Valence Band ◽  
Barrier Height ◽  
Field Effect ◽  
Phonon Scattering ◽  
Electron Tunneling ◽  
Negative Temperature ◽  
Field Effect Mobility ◽  
Channel Mobility ◽  
P Type ◽  
And Control

ABSTRACTIn this report we present results comparing lateral MOSFET properties of devices fabricated on Si-face (0001) and A-face (11-20) 4H-SiC, with nitric oxide passivation anneals. We observe a field-effect mobility of 33 cm2/V.s on p-type 5×1015 doped Si-face. These devices have a peak field-effect mobility which increases with temperature, indicative of a channel mobility limited by coulomb scattering. On 1×1016 p-type A-face SiC, the peak channel mobility is observed to be 80 cm2/V.s, with a negative temperature dependence, indicating that phonon-scattering effects dominate, with a much lower density of shallow acceptor traps. This > 2x higher channel mobility would result in a substantial decrease in on-resistance, hence lower power losses, for 4H-SiC power MOSFETs with voltage ratings below 2 kV. However, MOS C-V and gate leakage measurements indicate very different oxide and interface quality on each SiC face. For example, the Fowler-Nordheim (FN) conduction-band (CB) barrier height for electron tunneling at the SiO2/SiC interface is 2.8 eV on Si-face SiC, while it is 2.5 eV or less on A-face SiC. For the valence-band side, the effective FN barrier height at the valence-band (VB) side of only 1.6 eV on A-face SiC, while the VB barrier height is about 3.1 eV on Si-face SiC. Moreover, C-V of the MOS gate on A-face indicates the presence of a high-density of deep hole traps. It is apparent that oxides on alternative crystal faces, very promising in terms of channel mobility, require further study for complete understanding and control of the interface properties.

Effect of Graphite Cap for Implant Activation on Inversion Channel Mobility in 4H-SiC MOSFETs

2009 ◽  
Vol 615-617 ◽  
pp. 773-776 ◽  
Author(s):  
Harsh Naik ◽  
K. Tang ◽  
T. Paul Chow
Keyword(s):  
Low Temperature ◽  
Carrier Concentration ◽  
Threshold Voltage ◽  
Hall Mobility ◽  
Field Effect ◽  
Gate Oxide ◽  
Subthreshold Slope ◽  
Field Effect Mobility ◽  
Channel Mobility ◽  
Inversion Channel

The effects of using a graphite capping layer during implant activation anneal on the performance of 4H-SiC MOSFETs has been evaluated. Two sets of samples, one with the graphite cap and another without, with a gate oxide process consisting of a low-temperature deposited oxide followed by NO anneal at 1175°C for 2hrs were used for characterization. Various device parameters, particularly threshold voltage, subthreshold slope, field-effect mobility, inversion sheet carrier concentration and Hall mobility have been extracted for the two processes.

SiC Epi-Channel Lateral MOSFETs

2014 ◽  
Vol 778-780 ◽  
pp. 927-930
Author(s):  
Cheng Tyng Yen ◽  
Mietek Bakowski ◽  
Chien Chung Hung ◽  
Sergey A. Reshanov ◽  
Adolf Schöner ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Field Effect ◽  
Field Effect Mobility ◽  
High Concentration ◽  
P Type ◽  
Maximum Field

SiC lateral MOSFETs with multi-layers epi-channels were studied in this work. The epi-channel with a high concentration n-type epilayer sandwiched by two lightly doped p-type layers showed a maximum field effect mobility of 17 cm2/V.s, improved from 1.53 cm2/V.s of devices without epi-channels. These devices are normally-off with an average threshold voltage of 1.34V.

Effect of High Temperature Forming Gas Annealing on Electrical Properties of 4H-SiC Lateral MOSFETs with Lanthanum Silicate and ALD SiO2 Gate Dielectric

2018 ◽  
Vol 924 ◽  
pp. 482-485
Author(s):  
Min Seok Kang ◽  
Kevin Lawless ◽  
Bong Mook Lee ◽  
Veena Misra
Keyword(s):  
Threshold Voltage ◽  
Interfacial Layer ◽  
Field Effect ◽  
Lanthanum Oxide ◽  
Gate Dielectric ◽  
High Mobility ◽  
High Threshold ◽  
Field Effect Mobility ◽  
The Impact ◽  
Lanthanum Silicate

We investigated the impact of an initial lanthanum oxide (La2O3) thickness and forming gas annealing (FGA) conditions on the MOSFET performance. The FGA has been shown to dramatically improve the threshold voltage (VT) stability of 4H-SiC MOSFETs. The FGA process leads to low VTshift and high field effect mobility due to reduction of the interface states density as well as traps by passivating the dangling bonds and active traps in the Lanthanum Silicate dielectrics. By optimizing the La2O3interfacial layer thickness and FGA condition, SiC MOSFETs with high threshold voltage and high mobility while maintaining minimal VTshift are realized.

Process Optimisation for 4H-SiC MOSFET Applications

2006 ◽  
Vol 527-529 ◽  
pp. 1051-1054 ◽  
Author(s):  
Caroline Blanc ◽  
Dominique Tournier ◽  
Phillippe Godignon ◽  
D.J. Brink ◽  
Véronique Soulière ◽  
...  
Keyword(s):  
Field Effect ◽  
Oxidation Process ◽  
Gate Oxide ◽  
Process Optimisation ◽  
Field Effect Mobility ◽  
Oxide Formation ◽  
Step Procedure ◽  
P Type ◽  
Peak Value ◽  
Gas Precursor

We report on 4H-SiC MOSFET devices implemented on p-type <11-20>-oriented epitaxial layers, using a two-step procedure for gate oxide formation. First is a thin, dry, thermal SiO2 layer grown at 1050°C for 1 hour. Next, is a thick (50 nm) layer of complementary oxide deposited by PECVD using TEOS as gas precursor. With respect to the standard thermal oxidation process, this results in much improvement of the field effect mobility. For the best samples, we find a peak value in the range of 330 cm2/Vs while, on the full wafer, an average mobility of about 160 cm2/Vs is found. Up to now, this is one of the best results ever reported for 4H-SiC MOSFETs.

Gamma Irradiation Effects on 4H-SiC MOS Capacitors and MOSFETs

2006 ◽  
Vol 527-529 ◽  
pp. 1063-1066 ◽  
Author(s):  
Ayayi Claude Ahyi ◽  
S.R. Wang ◽  
John R. Williams
Keyword(s):  
Field Effect ◽  
Gamma Dose ◽  
Interface Traps ◽  
Valence Band Edge ◽  
Field Effect Mobility ◽  
Irradiation Effects ◽  
Mos Capacitors ◽  
Channel Mobility ◽  
Radiation Induced ◽  
Radiation Tolerant

The effects of gamma radiation on field effect mobility and threshold voltage have been studied for lateral n-channel 4H-SiC MOSFETs passivated with nitric oxide. MOS capacitors (n and p) and n-channel lateral MOSFETs were irradiated unbiased (floating contacts) for a total gamma dose of 6.8Mrad (Si). The MOS capacitors were used to study the radiation-induced interface traps and fixed oxide charge that affect the performance of the MOSFETs. Radiationinduced interface traps were observed near the SiC valence band edge and just above mid-gap, and field effect channel mobility was reduced by 18-20% following irradiation. Even so, 4HMOSFETs appear to be more radiation tolerant than Si devices.

Thin Film Transistors on Plastic Substrates Using Silicon Deposited by Microwave ECR-CVD

2003 ◽  
Vol 769 ◽  
Author(s):  
Lihong Teng ◽  
Wayne A. Anderson
Keyword(s):  
Thin Film ◽  
Threshold Voltage ◽  
Thin Film Transistors ◽  
Field Effect ◽  
Silicon Films ◽  
Subthreshold Swing ◽  
Field Effect Mobility ◽  
Current Ratio ◽  
Saturation Field ◽  
Plastic Substrates

AbstractThe properties of thin film transistors (TFT's) on plastic substrates with active silicon films deposited by microwave ECR-CVD were studied. Two types of plastic were used, PEEK and polyimide. The a-Si:H TFT deposited at 200°C on polyimide substrates showed a saturation field effect mobility of 4.5 cm2/V-s, a threshold voltage of 3.7 V, a subthreshold swing of 0.69 V/dec and an ON/OFF current ratio of 7.9×106, while the TFT fabricated on PEEK at 200°C showed a saturation field effect mobility of 3.9 cm2/V-s, a threshold voltage of 4.1 V, a subthreshold swing of 0.73 V/dec and an ON/OFF current ratio of 4×106. Comparison is made to TFT's with the Si deposited at 400°C on glass.

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