Surface Passivation of 4H-SiC for High Current Gain Bipolar Junction Transistors

2009 ◽  
Vol 615-617 ◽  
pp. 837-840 ◽  
Author(s):  
Yuki Negoro ◽  
Akihiko Horiuchi ◽  
Kensuke Iwanaga ◽  
Seiichi Yokoyama ◽  
Hideki Hashimoto ◽  
...  
Keyword(s):  
High Performance ◽  
Surface Passivation ◽  
Surface Recombination ◽  
Current Gain ◽  
Surface Recombination Velocity ◽  
Clear Correlation ◽  
Bipolar Junction Transistors ◽  
High Current ◽  
Blocking Voltage ◽  
Recombination Velocity

Surface passivation of 4H-SiC has been investigated for high current-gain bipolar junction transistors (BJTs). For the characterization of surface passivation, we have introduced the product “sp•Ls” of a surface recombination velocity (sp) and a surface diffusion length (Ls). The sp•Ls value was obtained by analyzing the I-V characteristics of pn diodes. Both BJTs and pn diodes were fabricated with several passivation methods. We have found clear correlation between the sp•Ls value and the current gain of the fabricated BJTs. Optimizing the surface passivation, we realized high performance BJTs with a current gain of 107 and a blocking voltage VCEO of 950 V.

Forward Active and Blocking Performance of 4H-SiC Bipolar Junction Transistors

2005 ◽  
Vol 888 ◽  
Author(s):  
Santhosh Balachandran ◽  
T. Paul Chow ◽  
Anant Agarwal
Keyword(s):  
High Voltage ◽  
Minority Carrier ◽  
Surface Recombination ◽  
Current Gain ◽  
Surface Recombination Velocity ◽  
Bipolar Junction Transistors ◽  
Carrier Lifetimes ◽  
Minority Carrier Lifetimes ◽  
Recombination Velocity ◽  
The Impact

ABSTRACTWe evaluate the performance capabilities and limitations of high voltage 4H-SiC based Bipolar Junction Transistors (BJTs). Experimental forward characteristics of a 4kV BJT are studied and simulations are employed to determine the factors behind the higher than expected specific on-resistance (Ron,sp) for the device. The impact of material (minority carrier lifetimes), processing (surface recombination velocity) and design (p contact spacing from the emitter mesa) parameters on the forward active performance of this device are discussed and ways to lower Ron,sp, below the unipolar level, and increase the gain (β) are examined. A correlation between the open base blocking behavior (forward blocking) and the current gain (forward active) for 4H-SiC based high-voltage BJTs with lightly doped collector regions is presented and experimental device characteristics are utilized to verify our numerical analysis.

Investigation of Surface Passivation in InAs/GaSb Strained-Layer-Superlattices Using Picosecond Excitation Correlation Measurement and Variable-Area Diode Array Surface Recombination Velocity Measurement

2005 ◽  
Vol 891 ◽  
Author(s):  
Zhimei Zhu ◽  
Elena Plis ◽  
Abdenour Amtout ◽  
Pallab Bhattacharya ◽  
Sanjay Krishna
Keyword(s):  
Infrared Detectors ◽  
Surface Passivation ◽  
Surface Recombination ◽  
Surface States ◽  
Depletion Region ◽  
Surface Recombination Velocity ◽  
Diode Array ◽  
Ammonium Sulfide ◽  
Picosecond Excitation ◽  
Recombination Velocity

ABSTRACTThe effect of ammonium sulfide passivation on InAs/GaSb superlattice infrared detectors was investigated using two complementary techniques, namely, picosecond excitation correlation (PEC) measurement and variable-area diode array (VADA) surface recombination velocity (SRV) measurement. PEC measurements were conducted on etched InAs/GaSb superlattice mesas, which were passivated in aqueous ammonium sulfide solutions of various strengths for several durations. The PEC signal's decay time constant (DTC) is proportional to carrier lifetimes. At 77 K the PEC signal's DTC of the as-grown InAs/GaSb superlattice sample was 2.0 ns, while that of the unpassivated etched sample was reduced to 1.2 ns by the surface states at the mesa sidewalls. The most effective ammonium sulfide passivation process increased the PEC signal's DTC to 10.4 ns. However it is difficult to isolate surface recombination from other processes that contribute to the lifetime using the PEC data, therefore a VADA SRV measurement was undertaken to determine the effect of passivation on surface recombination. The obtained SRV in the depletion region of the InAs/GaSb superlattice and GaSb junction was 1.1×106 cm/s for the unpassivated sample and 4.6×105 cm/s for the passivated sample. At 77 K the highest R0A value measured in our passivated devices was 2540 W cm2 versus 0.22 W cm2 for the unpassivated diodes. The results of the lifetime, the SRV and the R0A measurements indicate that ammonium sulfide passivation will improve the performance of InAs/GaSb superlattice infrared detectors.

Comparison of Total Losses of 1.2 kV SiC JFET and BJT in DC-DC Converter Including Gate Driver

2011 ◽  
Vol 679-680 ◽  
pp. 649-652 ◽  
Author(s):  
Jang Kwon Lim ◽  
Georg Tolstoy ◽  
Dimosthenis Peftitsis ◽  
Jacek Rabkowski ◽  
Mietek Bakowski ◽  
...  
Keyword(s):  
Threshold Voltage ◽  
Surface Recombination ◽  
Current Gain ◽  
Surface Recombination Velocity ◽  
Switching Frequency ◽  
Switching Losses ◽  
Insulator Interface ◽  
Gate Driver ◽  
Recombination Velocity ◽  
Emitter Junction

The 1.2 kV SiC JFET and BJT devices have been investigated and compared with respect to total losses including the gate driver losses in a DC-DC converter configuration. The buried grid, Normally-on JFET devices with threshold voltage of -50 V and -10V are compared to BJT devices with ideal semiconductor and passivating insulator interface and an interface with surface recombination velocity of 4.5•104 cm/s yielding agreement to the reported experimental current gain values. The conduction losses of both types of devices are independent of the switching frequency while the switching losses are proportional to the switching frequency. The driver losses are proportional to the switching frequency in the JFET case but to a large extent independent of the switching frequency in the BJT case. The passivation of the emitter junction modeled here by surface recombination velocity has a significant impact on conduction losses and gate driver losses in the investigated BJT devices.

Surface Recombination Investigation in Thin 4H-SiC Layers

1970 ◽  
Vol 17 (2) ◽  
pp. 119-124 ◽  
Author(s):  
Karolis GULBINAS ◽  
Vytautas GRIVICKAS ◽  
Haniyeh P. MAHABADI ◽  
Muhammad USMAN ◽  
Anders HALLÉN
Keyword(s):  
Surface Passivation ◽  
Surface Recombination ◽  
Atomic Layer ◽  
Surface Recombination Velocity ◽  
Lifetime Distributions ◽  
Carrier Lifetimes ◽  
Layer Deposition ◽  
Type Layer ◽  
Recombination Velocity ◽  
P Type

n- and p-type 4H-SiC epilayers were grown on heavily doped SiC substrates. The thickness of the p-type layer was 7 µm and the doping level around 1017 cm 3, while the n-type epilayers were 15 µm thick and had a doping concentration of 3 - 5*1015 cm 3. Several different surface treatments were then applied on the epilayers for surface passivation: SiO2 growth, Al2O3 deposited by atomic layer deposition, and Ar-ion implantation. Using collinear pump - probe technique the effective carrier lifetimes were measured from various places and statistical lifetime distributions were obtained. For surface recombination evaluation, two models are presented. One states that surface recombination velocity (SRV) is equal on both the passivation/epi layer interface (S2) and the deeper interface between the epilayer and the SiC substrate i. e. (S1 = S2). The other model is simulated assuming that SRV in the epilayer/substrate (S1) interface is constant while in the passivation layer/epilayer (S2) interface SRV can be varied S2 < S1. Empirical nomograms are presented with various parameters sets to evaluate S2 values. We found that on the investigated 4H-SiC surfaces S2 ranges from 3x104 to 5x104 assuming that the bulk lifetime is 4 (µs. In Ar+ implanted surfaces S2 is between (105 - 106) cm/s.http://dx.doi.org/10.5755/j01.ms.17.2.479

Enhanced Current Gain (>250) in 4H-SiC Bipolar Junction Transistors by a Deep-Level-Reduction Process

2012 ◽  
Vol 717-720 ◽  
pp. 1117-1122 ◽  
Author(s):  
Hiroki Miyake ◽  
Tsunenobu Kimoto ◽  
Jun Suda
Keyword(s):  
Room Temperature ◽  
Surface Passivation ◽  
Deep Level ◽  
Reduction Process ◽  
Current Gain ◽  
Bipolar Junction Transistors ◽  
High Current ◽  
Previous Record ◽  
Maximum Current ◽  
Level Reduction

We demonstrate 4H-SiC bipolar junction transistors (BJTs) with an enhanced current gain over 250. High current gain was achieved by utilizing optimized device geometry as well as optimized surface passivation, continuous epitaxial growth of the emitter-base junction, combined with an intentional deep-level-reduction process based on thermal oxidation to improve the lifetime in p-SiC base. We achieved a maximum current gain (β) of 257 at room temperature and 127 at 250°C for 4H-SiC BJTs fabricated on the (0001)Si-face. The gain of 257 is twice as large as the previous record gain. We also demonstrate BJTs on the (000-1)C-face that showed the highest β of 439 among the SiC BJTs ever reported.

Optimization of the Specific On-Resistance of 4H-SiC BJTs

2006 ◽  
Vol 527-529 ◽  
pp. 1429-1432 ◽  
Author(s):  
S. Balachandran ◽  
T. Paul Chow ◽  
Anant K. Agarwal
Keyword(s):  
High Voltage ◽  
Minority Carrier ◽  
Surface Recombination ◽  
Surface Recombination Velocity ◽  
Bipolar Junction Transistors ◽  
Carrier Lifetimes ◽  
Minority Carrier Lifetimes ◽  
Recombination Velocity ◽  
The Impact

We evaluate the performance capabilities and limitations of high voltage 4H-SiC based Bipolar Junction Transistors (BJTs). Experimental forward characteristics of a 4kV BJT are studied and simulations are employed to determine the factors behind the higher than expected specific onresistance (Ron,sp) for the device. The impact of material (minority carrier lifetimes), processing (surface recombination velocity) and design (p contact spacing from the emitter mesa) parameters on the forward active performance of this device are discussed and ways to lower Ron,sp, below the unipolar level, and increase the gain (β) are examined.

Orientation Dependence Of Surface Passivation For Semi-Insulating Gaas

1996 ◽  
Vol 421 ◽  
Author(s):  
I.P. Koutzarov ◽  
C.H. Edirisinghe ◽  
H.E. Ruda ◽  
L.Z. Jedral ◽  
Q. Liu ◽  
...  
Keyword(s):  
Band Gap ◽  
Surface Passivation ◽  
Dielectric Film ◽  
Surface Recombination ◽  
Orientation Dependence ◽  
Film Deposition ◽  
Surface Recombination Velocity ◽  
Strong Increase ◽  
X Ray ◽  
Recombination Velocity

AbstractWe report on the orientation dependence ((100), (110) and (111) ) of photoluminescence (PL), photoreflectance (PR) and Surface Photo-Voltage (SPV) for sulfur passivated bulk semiinsulating (SI) GaAs. Near band gap PL peak intensities (bound-exciton and acceptor-related) were enhanced following (NH4)2S or S2Cl2 treatment of GaAs for all orientations. The reduction of surface recombination velocity (from PL data) was orientation dependent and especially pronounced for the case of (111)A and (111)B orientations. The effect of thin dielectric layers deposited on S-treated surfaces was also investigated, particularly for (100) and (111)A orientations. SPV data shows a strong increase in the above band gap signal after both Streatment and dielectric film deposition, which was higher than that measured for only S-treated surfaces. PR data showed an increase in the interfacial electric field following deposition of dielectric film. The results of absolute S-surface coverage measurements using particle-induced X-ray emission measurements were correlated with the optical characteristics.

scholarly journals Surface passivation of germanium by atomic layer deposited Al2O3 nanolayers

2021 ◽  
Author(s):  
Wilhelmus J. H. Berghuis ◽  
Jimmy Melskens ◽  
Bart Macco ◽  
Roel J. Theeuwes ◽  
Marcel A. Verheijen ◽  
...  
Keyword(s):  
Surface Passivation ◽  
Surface Recombination ◽  
Atomic Layer ◽  
Extensive Study ◽  
Surface Recombination Velocity ◽  
Interface Charges ◽  
Layer Deposition ◽  
Recombination Velocity ◽  
Electronic Defects

AbstractSurfaces of semiconductors are notorious for the presence of electronic defects such that passivation approaches are required for optimal performance of (opto)electronic devices. For Ge, thin films of Al2O3 prepared by atomic layer deposition (ALD) can induce surface passivation; however, no extensive study on the effect of the Al2O3 process parameters has been reported. In this work we have investigated the influence of the Al2O3 thickness (1–44 nm), substrate temperature (50–350 °C), and post-deposition anneal (in N2, up to 600 °C). We demonstrated that an effective surface recombination velocity as low as 170 cm s−1 can be achieved. The role of the GeOx interlayer as well as the presence of interface charges was addressed and a fixed charge density $${Q}_{\mathrm{f}}=$$ Q f = −(1.8 ± 0.5) × 1012 cm−2 has been found. The similarities and differences between the passivation of Ge and Si surfaces by ALD Al2O3 prepared under the same conditions are discussed. Graphic Abstract

Improved Current Gain in 4H-SiC BJTs Passivated with Deposited Oxides Followed by Nitridation

2011 ◽  
Vol 679-680 ◽  
pp. 698-701
Author(s):  
Hiroki Miyake ◽  
Tsunenobu Kimoto ◽  
Jun Suda
Keyword(s):  
Surface Passivation ◽  
Passivation Layer ◽  
Current Gain ◽  
Bipolar Junction Transistors ◽  
High Current ◽  
Post Deposition Annealing ◽  
Thermally Grown Oxides ◽  
Post Deposition ◽  
Thermally Grown

We report the improvement of current gain in 4H-SiC bipolar junction transistors (BJTs) by using deposited oxides as a surface passivation layer. Various post-deposition annealing processes were investigated. We successfully demonstrated SiC BJTs with a high current gain (β) of 86 using deposited oxides annealed in NO. This is 70% higher current gain compared with that of BJTs with the same structure with conventional thermally-grown oxides.

A Comparative Study of Surface Passivation on SiC BJTs with High Current Gain

2007 ◽  
Vol 556-557 ◽  
pp. 631-634
Author(s):  
Hyung Seok Lee ◽  
Martin Domeij ◽  
Carl Mikael Zetterling ◽  
Mikael Östling ◽  
Einar Ö. Sveinbjörnsson
Keyword(s):  
Surface Passivation ◽  
Surface Recombination ◽  
Thermally Grown Oxide ◽  
The Other ◽  
Current Gain ◽  
High Current ◽  
Different Types ◽  
Passivation Layers ◽  
Recombination Current ◽  
Dc Current

The effect of the different types of passivation layers on the current gain of SiC BJTs has been investigated. Measurements have been compared for BJTs passivated with thermal SiO2, plasma deposited (PECVD) SiO2 and BJTs without passivation. The maximum DC current gain of BJTs with thermal SiO2 was about 62 at IC=20 mA and Vce=40 V. On the other hand, the BJTs with a passivation by PECVD SiO2 had a DC current gain of only 25. The surface recombination current was extracted from measurements with BJTs of different emitter widths. The surface recombination current of BJTs with a thermally grown oxide was about 25 % lower than unpassivated BJTs and 65 % lower than that of PECVD passivated BJTs.

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