Plasma‐enhanced chemical‐vapor‐deposited oxide for low surface recombination velocity and high effective lifetime in silicon

ABSTRACTThe carrier recombination rate in high-quality FZ and Cz silicon substrates is studied by contactless infrared and microwave absorption techniques. Different surface treatments covering a wide range of surface recombination velocity have been used for the separation of bulk and surface recombination components and evaluating of the efficiency of passivation. Limitations of effective lifetime approach are analyzed specific for low and high injection level. Sensitivity limits of the techniques for iron contamination are discussed

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Interface Study Of Nanocrystalline Silicon and Crystalline Silicon Using Microwave Photoconductivity Decay

MRS Proceedings ◽

10.1557/proc-0910-a04-04 ◽

2006 ◽

Vol 910 ◽

Author(s):

Mahdi Farrokh Baroughi ◽

Siva Sivoththaman

Keyword(s):

Crystalline Silicon ◽

Surface Recombination ◽

Chemical Vapor ◽

Nanocrystalline Silicon ◽

Interface Region ◽

Surface Recombination Velocity ◽

Si Substrate ◽

Photoconductivity Decay ◽

Recombination Velocity ◽

Si Films

AbstractThis paper presents a measurement technique for studying of the interface between a nanocrystalline silicon (nc-Si) film and a crystalline silicon (c-Si) substrate using microwave photoconductivity decay (MWPCD). The nc-Si films were deposited using plasma enhanced chemical vapor deposition of highly hydrogen-diluted silane. The films were deposited on both sides of the high purity float-zone (FZ) Si wafers. The high resolution transmission electron microscope (HRTEM) analysis of the interface and the characterization of the effective excess carrier lifetime of the samples using MWPCD revealed the following results: (i) The crystallinity of the deposited nc-Si films is very high. The nc-Si film follows the crystal orientation of the substrate such that not a well-defined boundary between nc-Si film and the c-Si substrate is observed. (ii) A surface recombination velocity of less than 10 cm/s was measured for the interface region of the nc-Si/c-Si junctions. (iii) A small discontinuity in the band-energy diagram of the interface region was observed.

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The Performance of Hg0.8Cd0.2Te Photodetectors by Using Photo Surface Treatment

International Journal of High Speed Electronics and Systems ◽

10.1142/s0129156497000287 ◽

1997 ◽

Vol 08 (04) ◽

pp. 703-717 ◽

Cited By ~ 1

Author(s):

Y. K. Su ◽

C. T. Lin

Keyword(s):

Surface Treatment ◽

Surface Recombination ◽

Chemical Vapor ◽

Lower Surface ◽

Treatment Method ◽

Cdte Layer ◽

Surface Recombination Velocity ◽

Noise Power ◽

Cdte Passivation ◽

Recombination Velocity

The principal aim of this paper is to propose an easy, vapor phase, and reproducible photo surface treatment method to improve the device performance of the Hg0.8Cd0.2Te photoconductive detector. Experimental results, including Auger electron spectroscopy (AES), MIS leakage current, 1/f noise voltage spectrum, 1/fknee frequency, responsivity Rλ, and specific detectivity D* for stacked photo surface treatment and ZnS or CdTe passivation layers are presented. By using this method, we found that there is no accumulation of Hg in the oxide/HgCdTe interface regions. Since the photo chemical vapor native oxidation is a dry oxidation method deposited at a low temperature, it can effectively suppress the Hg enhancement and the Cd depletion effects and thus obtain a high quality interface. We also found that the photo surface treatment in combination with thermally eveporated ZnS or CdTe layer would shift the 1/fknee under 100Hz in an electrical field under 50 V/cm, reduce the noise power spectrum, and achieve a lower surface recombination velocity S of 300 cm/sec as well as a high D* of 3 × 1010 cm [Formula: see text] for blackbody radiation. It was also found that HgCdTe photoconductor passivated with stacked layers shows improved interface properties when compared to the photoconductor passivated with a single passivation layer.

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Ultrathin Oxide Passivation Layer by Rapid Thermal Oxidation for the Silicon Heterojunction Solar Cell Applications

International Journal of Photoenergy ◽

10.1155/2012/753456 ◽

2012 ◽

Vol 2012 ◽

pp. 1-5 ◽

Cited By ~ 4

Author(s):

Youngseok Lee ◽

Woongkyo Oh ◽

Vinh Ai Dao ◽

Shahzada Qamar Hussain ◽

Junsin Yi

Keyword(s):

Solar Cell ◽

Thermal Oxidation ◽

Oxide Layer ◽

Silicon Oxide ◽

Surface Recombination ◽

Surface Recombination Velocity ◽

Effective Lifetime ◽

Silicon Oxide Layer ◽

Rapid Thermal Oxidation ◽

Recombination Velocity

It is difficult to deposit extremely thin a-Si:H layer in heterojunction with intrinsic thin layer (HIT) solar cell due to thermal damage and tough process control. This study aims to understand oxide passivation mechanism of silicon surface using rapid thermal oxidation (RTO) process by examining surface effective lifetime and surface recombination velocity. The presence of thin insulating a-Si:H layer is the key to get highVocby lowering the leakage current (I0) which improves the efficiency of HIT solar cell. The ultrathin thermal passivation silicon oxide (SiO2) layer was deposited by RTO system in the temperature range 500–950°C for 2 to 6 minutes. The thickness of the silicon oxide layer was affected by RTO annealing temperature and treatment time. The best value of surface recombination velocity was recorded for the sample treated at a temperature of 850°C for 6 minutes at O2flow rate of 3 Lpm. A surface recombination velocity below 25 cm/s was obtained for the silicon oxide layer of 4 nm thickness. This ultrathin SiO2layer was employed for the fabrication of HIT solar cell structure instead of a-Si:H, (i) layer and the passivation and tunneling effects of the silicon oxide layer were exploited. The photocurrent was decreased with the increase of illumination intensity and SiO2thickness.

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