High Integrity SiO2/Al2O3 Gate Stack for Normally-off GaN MOSFET

2013 ◽  
Vol 1561 ◽  
Author(s):  
Hiroshi Kambayashi ◽  
Takehiko Nomura ◽  
Hirokazu Ueda ◽  
Katsushige Harada ◽  
Yuichiro Morozumi ◽  
...  
Keyword(s):  
Field Effect ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
Gate Insulator ◽  
Oxide Semiconductor ◽  
Breakdown Field ◽  
Mos Transistors ◽  
Gate Stack ◽  
High Integrity

ABSTRACTHigh integrity SiO2/Al2O3 gate stack has been demonstrated for GaN metal-oxide-semiconductor (MOS) transistors. The SiO2 film formed on GaN by the microwave-excited plasma enhanced chemical vapor deposition (MW-PECVD) exhibits good properties compared that by the LP (Low Pressure)-CVD. Then, by incorporating the advantages of both of SiO2 with a high insulating and Al2O3 with good interface characteristics, the SiO2/Al2O3 gate stack structure has been employed in GaN MOS devices. The structure shows a low interface state density between gate insulator and GaN, a high breakdown field, and a large charge-to-breakdown by applying 3-nm Al2O3. The SiO2/Al2O3 gate stack has also been applied to AlGaN/GaN hybrid MOS heterojunction field-effect transistor (HFET) and the HFET shows excellent properties with the threshold voltage of 4.2 V and the maximum field-effect mobility of 192 cm2/Vs.

Investigation of the off-current in amorphous silicon thin film transistors for SiO2 and SiNx. gate insulators

1996 ◽  
Vol 424 ◽  
Author(s):  
Jeong Hyun Kim ◽  
Woong Sik Choi ◽  
Chan Hee Hong ◽  
Hoe Sup Soh
Keyword(s):  
Thin Film ◽  
Amorphous Silicon ◽  
Thin Film Transistors ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
Gate Insulator ◽  
Defect States ◽  
Silicon Thin Film ◽  
Pressure Chemical

AbstractThe off current behavior of hydrogenated amorphous silicon (a-Si:H) thin film transistors (TFTs) with an atmospheric pressure chemical vapor deposition (APCVD) silicon dioxide (SiO2) gate insulator were investigated at negative gate voltages. The a-Si:H TFT with SiO2 gate insulator has small off currents and large activation energy (Ea) of the off current compared to the a-Si:H TFT with SiNx gate insulator. The holes induced in the channel by negative gate voltage seem to be trapped in the defect states near the a-Si:H/SiO2 interface. The interface state density in the lower half of the band gap of a-Si:H/SiO2 appears to be much higher than that for a-Si:H/SiNx.

Fabrication and Characterization of 4H-SiC MOSFET with MOCVD-Grown Al2O3 Gate Insulator

2007 ◽  
Vol 556-557 ◽  
pp. 787-790 ◽  
Author(s):  
Shiro Hino ◽  
Tomohiro Hatayama ◽  
Naruhisa Miura ◽  
Tatsuo Oomori ◽  
Eisuke Tokumitsu
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Vapor ◽  
Drain Current ◽  
Interface State ◽  
State Density ◽  
Gate Insulator ◽  
Organic Chemical ◽  
Mos Capacitors ◽  
Significant Difference ◽  
Metal Organic

We have fabricated and characterized MOS capacitors and lateral MOSFETs using Al2O3 as a gate insulator. Al2O3 films were deposited by metal-organic chemical vapor deposition (MOCVD) at temperatures as low as 190 oC using tri-ethyl-aluminum and H2O as precursors. We first demonstrate from the capacitance – voltage (C-V) measurements that the Al2O3/SiC interface has lower interface state density than the thermally-grown SiO2/SiC interface. No significant difference was observed between X-ray photoelectron spectroscopy (XPS) Si 2p spectrum from the Al2O3/SiC interface and that from the SiC substrate, which means the SiC substrate was not oxidized during the Al2O3 deposition. Next, we show that the fabricated lateral SiC-MOSFETs with Al2O3 gate insulator have good drain current – drain voltage (ID-VD) and drain current – gate voltage (ID-VG) characteristics with normally-off behavior. The obtained peak values of field-effect mobility (μFE) are between 68 and 88 cm2/Vs.

Fabrication of High Quality MOS Devices for Application in Hazardous Environments Based on RTP Gate Dielectrics with In Situ RTCVD of Polysilicon Gates

1993 ◽  
Vol 300 ◽  
Author(s):  
B. Fröschle ◽  
H.P. Bruemmer ◽  
W. Lang ◽  
K. Neumeier ◽  
P. Ramm
Keyword(s):  
Threshold Voltage ◽  
Gate Dielectrics ◽  
Chemical Vapor ◽  
Process Variations ◽  
Interface State ◽  
State Density ◽  
Breakdown Field ◽  
Polysilicon Gate ◽  
Radiation Induced

ABSTRACTProcess modules for MOS gate fabrication were developed which can be completed subsequently in one RTP reactor: atmospheric process sequences for gate oxides and oxynitrides as well as low pressure chemical vapor deposition of polysilicon (RTCVD). Prior to the Rapid Thermal Oxidation (RTO), the wafers were treated with a Rapid Thermal Cleaning process (RTC) in H2/Ar ambient. After the desoxidation step the RTO was done in O2/H2/Ar followed by an anneal (RTA) for the gate oxide or a nitridation in NH3 (RTN) and reoxidation for the oxynitrides, respectively. The polysilicon gate electrode was fabricated either by RTCVD in situ or in a conventional furnace reactor. The two-step RTCVD process resulted in a very good thickness uniformity for the polysilicon layers of 3% (3mm from the edge). The influence of the process variations on breakdown field, fixed oxide charge, interface state density, flatband voltage, and threshold voltage of the different types of gate dielectrics was investigated. The charges and voltages were determined by LF-HF CV measurements. In order to characterize the radiation tolerance of electronic devices, radiation induced flatband and threshold voltage shifts as well as the build up of interface charges were determined. The irradiation was performed at a Co - 60 gamma source. Breakdown fields in the range of 19 MV/cm, interface state densities of less than 109 eV−1cm−2, and radiation induced threshold voltage shifts below 0.1 V after 1.5 Mrad(Si) were obtained.

Modelling of the Anomalous Field-Effect Mobility Peak of O-Ta2Si/4H-SiC High-k MOSFETs Measured in Strong Inversion

2006 ◽  
Vol 527-529 ◽  
pp. 1059-1062
Author(s):  
Amador Pérez-Tomás ◽  
Miquel Vellvehi ◽  
Narcis Mestres ◽  
José Millan ◽  
P. Vennegues ◽  
...  
Keyword(s):  
Field Effect ◽  
Inversion Layer ◽  
Interface State ◽  
State Density ◽  
Gate Insulator ◽  
Coulomb Scattering ◽  
Field Effect Mobility ◽  
Tunnel Current ◽  
High K ◽  
Strong Inversion

A high field-effect mobility peak (50 cm2/Vs) has been extracted in (0001) Si face 4HSiC MOSFETs with oxidized Ta2Si (O-Ta2Si) high-k dielectric (k~20) as gate insulator, with their gates in the strong inversion regime. The interface state density (Dit) has not been particularly reduced in O-Ta2Si capacitors. This anomalous mobility enhancement is explained in terms of Coulomb scattering reduction and quantified using a physical model based on the Lombardi mobility model. The anomalous mobility increase is closely related to the leakage current, and also to the gate breakdown mechanism. We propose a model for which the observed interfacial SiO2 tunnel current combined with Poole-Frenkel mechanisms at the O-Ta2Si gate generates a sufficiently low abrupt transition in gate breakdown to obtain an effective passivation of the interface traps. Under these conditions, the increase of free carriers in the inversion layer induced by the gate leakage diminishes the effect of the interface trap Coulomb scattering.

Heteroepitaxial Growth of A1203 Thin Films on Si By Lpcvd

1988 ◽  
Vol 116 ◽  
Author(s):  
M. Ishida ◽  
I. Katakabe ◽  
N. Ohtake ◽  
T. Nakamura
Keyword(s):  
Thin Films ◽  
Chemical Vapor ◽  
Interface State ◽  
State Density ◽  
Gate Insulator ◽  
Heteroepitaxial Growth ◽  
Mos Capacitors ◽  
Pressure Chemical ◽  
Relationship Of ◽  
Substrate Temperatures

AbstractHeteroepitaxial A1203 thin films were grown successfully on Si(lO0) substrates by low—pressure chemical vapor deposition (LP—CVD). The growth was performed at a pressure of 30 Torr by pyrolysis of N2 bubbled AI(CH3)3 and N20 at substrate temperatures above 1000ºC.RHEED patterns indicated that the grown films were ɤ—Al203 single crystals with an orientation relationship of ɤ—Al203(l00)//Si(l00). The ɤ—A1203 films were stable and did not show phase transition after a 1140ºC heat—treatment for 2hr. MOS capacitors with 500—Å—thick A1203 films as a gate insulator showed highfrequency capacitance—voltage (C—V) curves without hysteresis. The A1203 interface state density determined from quasi—static C—V measurements was 1.7 X 1011cm-2eV-1. It can be seen that ɤ—Al203 film is a promising new insulator for Si on Insulator (SOI) structures.

Preannealing Effect on Mobility of N-/Al-Coimplanted and Over-Oxidized 4H-SiC MOSFETs

2010 ◽  
Vol 645-648 ◽  
pp. 487-490 ◽  
Author(s):  
Yuichiro Nanen ◽  
Bernd Zippelius ◽  
Svetlana Beljakowa ◽  
Lia Trapaidze ◽  
Michael Krieger ◽  
...  
Keyword(s):  
Mass Spectroscopy ◽  
Field Effect ◽  
Field Effect Transistors ◽  
Interface State ◽  
State Density ◽  
Metal Oxide Semiconductor ◽  
Interface State Density ◽  
Oxide Semiconductor ◽  
Effective Mobility ◽  
Secondary Ion

The authors investigated the effect of preannealing on N-/Al-coimplanted and over-oxidized Metal-Oxide-Semiconductor Field Effect Transistors (MOSFETs). The preannealing process causes a decrease of the Hall mobility and the effective mobility, and an increase of the interface state density. Secondary ion mass spectroscopy (SIMS) measurements revealed that the N concentration at the SiO2/SiC interface in preannealed samples is lower than in not-preannealed samples, which might be the reason for in the increase of the interface state density. In MOSFETs without preannealing, more N atoms are piled up at the SiO2/SiC interface, leading to the lower interface state density and higher mobility.

High-Mobility SiC MOSFETs with Chemically Modified Interfaces

2015 ◽  
Vol 821-823 ◽  
pp. 749-752 ◽  
Author(s):  
Daniel J. Lichtenwalner ◽  
Lin Cheng ◽  
Sarit Dhar ◽  
Anant K. Agarwal ◽  
Scott Allen ◽  
...  
Keyword(s):  
Nitric Oxide ◽  
Field Effect ◽  
Alkaline Earth ◽  
Phonon Scattering ◽  
High Mobility ◽  
Interface Layer ◽  
Interface State ◽  
State Density ◽  
Oxide Semiconductor ◽  
Alkaline Earth Elements

Alkali (Rb, Cs) and alkaline earth elements (Sr, Ba) provide SiO2/SiC interface conditions suitable for obtaining high metal-oxide-semiconductor field-effect-transistor (MOSFET) channel mobility on the 4H-SiC Si-face (0001), without the standard nitric oxide (NO) anneal. The alkali elements Rb and Cs result in field-effect mobility (μFE) values >25 cm2/V.s, and the alkaline earth elements Sr and Ba resulted in higher μFE values of 40 and 85 cm2/V.s, respectively. The Ba-modified MOSFETs show a slight decrease in mobility with heating to 150 °C, as expected when mobility is not interface-trap-limited, but phonon-scattering-limited. The interface state density is lower than that obtained with nitric oxide (NO) passivation. Devices with a Ba interface layer maintain stable mobility and threshold voltage under ±2 MV/cm gate bias stress at 175 °C, indicating no mobile ions.

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