Improvement of Minority Carrier Lifetime in Thick 4H-SiC Epi-layers by Multiple Thermal Oxidations and Anneals

2013 ◽  
Vol 1538 ◽  
pp. 329-333 ◽  
Author(s):  
Lin Cheng ◽  
Michael J. O’Loughlin ◽  
Alexander V. Suvorov ◽  
Edward R. Van Brunt ◽  
Albert A. Burk ◽  
...  
Keyword(s):  
High Temperature ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Power Devices ◽  
Oxidation Treatment ◽  
Temperature Oxidation ◽  
Oxidation Step ◽  
High Temperature Anneal ◽  
Lifetime Enhancement

ABSTRACTThis paper details the development of a technique to improve the minority carrier lifetime of 4H-SiC thick (≥ 100 μm) n-type epitaxial layers through multiple thermal oxidations. A steady improvement in lifetime is seen with each oxidation step, improving from a starting ambipolar carrier lifetime of 1.09 µs to 11.2 µs after 4 oxidation steps and a high-temperature anneal. This multiple-oxidation lifetime enhancement technique is compared to a single high-temperature oxidation step, and a carbon implantation followed by a high-temperature anneal, which are traditional ways to achieve high ambipolar lifetime in 4H-SiC n-type epilayers. The multiple oxidation treatment resulted in a high minimum carrier lifetime of 6 µs, compared to < 2 µs for other treatments. The implications of lifetime enhancement to high-voltage/high-current 4H-SiC power devices are also discussed.

Enhancement of Minority Carrier Lifetime in Ultra-High Voltage 4H-SiC PiN Diodes by Carbon-Film Annealing

2020 ◽  
Vol 1014 ◽  
pp. 137-143
Author(s):  
Wen Ting Zhang ◽  
Yun Lai An ◽  
Yi Ying Zha ◽  
Ling Sang ◽  
Jing Hua Xia ◽  
...  
Keyword(s):  
High Temperature ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Carbon Film ◽  
Minority Carrier Lifetime ◽  
Pin Diodes ◽  
High Temperature Anneal ◽  
Thin Carbon ◽  
Drift Layer ◽  
Lifetime Enhancement

A novel process is developed for minority carrier lifetime enhancement in ultra-high 4H-SiC PiN diodes. It comprises two separate processes. Firstly, the ultra-thick epitaxial grown drift layer (200μm) covered with a protective thin carbon film is subject to a 1500°C high-temperature anneal process in Ar atmosphere for 2 hours. Secondly, a surface passivation process is adopted to reduce the surface recombination rate. μ-PCD tests show that after high-temperature anneal, the thick drift layer shows a minority carrier lifetime increase to about 1.6 μs. PiN diodes based on the novel process are fabricated and their electric characteristics are measured. Results show a low specific on-resistance of 16.3 mΩ·cm2 at 25°C and 14 mΩ·cm2 at 125 °C. Compared with simulation results, it is shown that its effective minority carrier lifetime increase to about 5μs .Our study demonstrates that the developed novel process is effective in minority carrier lifetime enhancement in ultra-voltage 4H-SiC PiN diodes.

Lifetime Enhancement of 4H-SiC PiN Diodes Using High Temperature Oxidation Treatment

2018 ◽  
Vol 924 ◽  
pp. 440-443
Author(s):  
Yeganeh Bonyadi ◽  
Peter M. Gammon ◽  
Olayiwola Alatise ◽  
Roozbeh Bonyadi ◽  
Philip A. Mawby
Keyword(s):  
High Temperature ◽  
Thermal Oxidation ◽  
Carrier Lifetime ◽  
Drift Region ◽  
Electrical Characteristics ◽  
Pin Diodes ◽  
Oxidation Treatment ◽  
Temperature Oxidation ◽  
Bipolar Devices ◽  
Minority Carriers

In this paper, the application of a high temperature thermal oxidation and annealing process to 4H-SiC PiN diodes with 35 μm thick drift regions is explored, the aim of which was to increase the carrier lifetime in the 4H-SiC. Diodes were fabricated using 4H-SiC material and underwent a thermal oxidation in dry pure O2 at 1550◦C followed by an argon anneal at the same temperature. Reverse recovery tests indicated a carrier lifetime increase of around 42% which is due to increase of excessive minority carriers in the drift region. The switching results illustrate that the use of this process is a highly effective and efficient way of enhancing the electrical characteristics of high voltage 4H-SiC bipolar devices.

Impact of Carrier Lifetime Enhancement Using High Temperature Oxidation on 15 kV 4H-SiC P-GTO Thyristor

2017 ◽  
Vol 897 ◽  
pp. 587-590 ◽  
Author(s):  
Sei Hyung Ryu ◽  
Daniel J. Lichtenwalner ◽  
Edward van Brunt ◽  
Craig Capell ◽  
Michael J. O’Loughlin ◽  
...  
Keyword(s):  
High Temperature ◽  
Carrier Lifetime ◽  
Voltage Drop ◽  
Current Gain ◽  
Slight Reduction ◽  
Temperature Oxidation ◽  
Forward Voltage Drop ◽  
P Type ◽  
The Impact ◽  
Lifetime Enhancement

The impact of the lifetime enhancement process using high temperature thermal oxidation method on 4H-SiC P-GTOs was investigated. 15 kV 4H-SiC P-GTOs with 140 μm thick drift layers, with and without 1450°C lifetime enhancement oxidation (LEO) process, were compared. The LEO process increased the average carrier lifetime in p-type epi layer from 0.9 μs to 6.25 μs, and it was observed that the effectiveness of the lifetime enhancement process was very sensitive to the doping concentration. The device with the LEO process showed a significant reduction in forward voltage drop and a substantially lower holding current, as expected from the carrier lifetime measurements. However, a slight reduction in blocking capability was also observed from the devices treated with LEO process. The common emitter current gain (β) of the wide base test NPN BJT was approximately 10X higher for the wafer with LEO process.

High Carrier Lifetime Bulk-Grown 4H-SiC Substrates for Power Applications

2006 ◽  
Vol 911 ◽  
Author(s):  
David Malta ◽  
J.R. Jenny ◽  
V.F. Tsvetkov ◽  
M. Das ◽  
St. G. Müller ◽  
...  
Keyword(s):  
Carrier Lifetime ◽  
Minority Carrier ◽  
Deep Level ◽  
Minority Carrier Lifetime ◽  
Drift Region ◽  
Disordered Lattice ◽  
High Temperature Anneal ◽  
Decay Times ◽  
Photoconductivity Decay ◽  
High Carrier

AbstractA thermal anneal process has been developed that significantly enhances minority carrier lifetime (MCL) in bulk-grown substrates. Microwave photoconductivity decay (MPCD) measurements on bulk grown substrates subjected to this process have exhibited decay times in excess of 35 μs. Electron Beam Induced Current (EBIC) measurements indicated a minority carrier diffusion length (MCDL) of 65 μm resulting in a calculated MCL of 15 μs, well within the range of that measured by MPCD. Deep level transient spectroscopic (DLTS) analysis of samples subjected to this anneal process indicated that a significant reduction of deep level defects, particularly Z1/2, may account for the significantly enhanced lifetimes. The enhanced lifetime is coincident with a transformation of the original as-grown crystal into a strained or disordered lattice configuration as a result of the high temperature anneal process. PiN diodes were fabricated employing 350 μm thick bulk-grown substrates as the intrinsic drift region and thin p- and n-type epitaxial layers on either face of the substrate to act as the anode and cathode, respectively. Conductivity modulation was achieved in these diodes with a 10x effective carrier concentration increase over the background doping as extracted from the differential on-resistance. Significant stacking fault generation observed during forward operation served as additional evidence of conductivity modulation and underscores the importance of reducing dislocation densities in substrates in order to produce a viable bulk-grown drift layer.

AlxGa1−xAs minority carrier lifetime enhancement at low temperatures

2013 ◽  
Vol 103 (13) ◽  
pp. 132102 ◽  
Author(s):  
Stefan Heckelmann ◽  
David Lackner ◽  
Frank Dimroth ◽  
Andreas W. Bett
Keyword(s):  
Low Temperatures ◽  
Carrier Lifetime ◽  
Minority Carrier ◽  
Minority Carrier Lifetime ◽  
Lifetime Enhancement
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