Reversible changes in temperature dependence of electric conductivity of hydrogenated amorphous silicon caused by proton irradiation

Sato, Shin-ichiro; Ohshima, Takeshi

doi:10.1016/j.jnoncrysol.2014.03.026

Cited by 3 publications

(4 citation statements)

References 32 publications

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“…The FF improvement may originate from two aspects: (i) the diffused BSF has the better conductivity than a‐Si:H(n + ), the former is the conductivity of ∼10 5 S cm −1 (calculated according to 30 Ω/□ from Refs. ), and the latter ∼10 −5 S cm −1 , which leads to the decrease of the series resistivity ( R s ) when a‐Si:H(i/n + ) BSF was replaced by the diffused one; (ii) the Δ E c do not exist in diffused homojunction BSF to avoid the transport loss of majority carriers in the interface (Figure (b)).…”

Section: Discussionmentioning

confidence: 99%

Single‐Side Heterojunction Solar Cell with Microcrystalline Silicon Oxide Emitter and Diffused Back Surface Field

Yang

Chen

Liu

et al. 2017

Physica Status Solidi (a)

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The goal of high efficiency in Si solar cells has been developed to a close limit by Si heterojunction (SHJ) scheme. The further work should aim to simplify its fabrication process for the reduction of cost. In this study, a scheme single-side heterojunction solar cell with hydrogenated microcrystalline silicon oxide emitter ((mc-SiO x :H(p þ )) and diffused back surface field (BSF) was presented, to save the flip of wafers and the number of vacuum chambers. The device performance evolution was performed by AFORS-HET simulation and experiments. It is demonstrated that FF of the solar cell is improved using diffused BSF to replace the intrinsic and doped stack hydrogenated amorphous silicon (a-Si:H(n þ /i)) layer in HIT solar cell, but J sc and V oc decreased. The former ascribes to the better conductivity of diffused BSF and band offset free in homojunction, the later the free carrier absorption in diffused region and the removal of rear a-Si:H passivation layer. Further, the introduction of mc-SiO x :H(p þ ) emitter can compensate for the loss of J sc above and increase FF, again, due to its wide band gap and high electrical conductivity, leading to a device performance similar to routine HIT device. This work provides a candidate for the roadmap of SHJ solar cells.

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Section: Discussionmentioning

confidence: 99%

Single‐Side Heterojunction Solar Cell with Microcrystalline Silicon Oxide Emitter and Diffused Back Surface Field

Yang

Chen

Liu

et al. 2017

Physica Status Solidi (a)

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“…6 Balberg plot of the a-Si:H films deposited at different pressure (ESC) regime). There seems to be Variable Range Hopping (VRH) conduction in these films at lower temperature (T < 348 K) which originates from localised states where the electrons hop to a neighbouring site [21]. The transport model for this is described as [22] …”

Section: Transport Propertymentioning

confidence: 99%

Effect of Pressure on Bonding Environment and Carrier Transport of a-Si:H Thin Films Deposited Using 27.12 MHz Assisted PECVD Process

Chaudhary

Sharma

Sudhakar

et al. 2016

Silicon

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Investigation of carrier transport in hydrogenated amorphous silicon (a-Si:H) thin films deposited at various pressures (0.03 -0.53 Torr) using 27.12 MHz assisted high frequency Plasma Enhanced Chemical vapor Deposition (PECVD) process is presented. From results of Steady State Photocarrier Grating (SSPG) the carrier diffusion length was found to vary from 0.098 -0.189 μm. Moreover a direct influence of ambipolar diffusion length was observed with the transport mechanism for deposition pressure in the range (0.13 -0.53 Torr). There was a correlation observed for photosensitivity and microstructure parameter with mobility lifetime (μτ ) product and diffusion length of carriers. Diffusion length and μτ product were observed to be maximum (0.189 μm and 0.471 x 10 −8 cm 2 V −1 ) for the film having high photosensitivity (7.2x10 3 ) deposited at a rate ∼1.39Å/s at 0.53 Torr deposition pressure. In addition to electrical transport properties, the effect of deposition pressure on structural and optical properties was also studied using various characterization tools such as Raman, UV-Vis and infrared spectroscopy.

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“…The dependence of hopping electrical conductivity on temperature in disordered semiconductors with point structural defects was studied earlier [14][15][16][17][18]. For example, in [14], hopping photoconductivity of a-Si:H films was measured before and after their irradiation with protons, and the data were interpreted according to the Mott model of hopping electrical conductivity [19].…”

Section: Introductionmentioning

confidence: 99%

“…The interpretation of the experimental data in [21] on photo-and electrical conductivity was based on the parameterization of the Gaussian electronic density of states and the postulation of the temperature and energy dependence of the hopping mobility with fitting parameters without its theoretical justification. Moreover, in [14][15][16][17][18][19][20][21], hopping electrical conductivity via three-charge-state point defects could not be described without using fitting parameters (see also [22,23]).…”

Section: Introductionmentioning

confidence: 99%

DC hopping photoconductivity via three-charge-state point defects in partially disordered semiconductors

Poklonski¹,

Anikeev²,

Вырко³

2022

Phys. Scr.

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The stationary (DC) hopping photoconductivity caused by the migration of electrons via intrinsic point t-defects of the same type with three charge states (-1, 0, and +1 in units of elementary charge) is theoretically studied. It is assumed that t-defects are randomly (Poissonian) distributed over a crystal and hops of single electrons occur only via t-defects in the charge states (-1), (0) and (0), (+1). Under the influence of intercenter illumination nonequilibrium charge states (-1) and (+1) of defects are generated due to photostimulated electron transitions between pairs of defects in the charge states (0). During the recombination of nonequilibrium charge states (-1) and (+1) of defects, pairs of defects in the charge states (0) are formed. It is assumed that illumination does not heat the crystal, i.e. does not increase the coefficient of thermal ionization of t-defects. The dependence of the ratio of photoconductivity to dark hopping electrical conductivity on the ratio of photoionization coefficient (γ) of neutral t-defects to coefficient of "capture" (α) of an electron from a negatively charged to a positively charged t-defect is calculated. The calculations of hopping photoconductivity were carried out for the partially disordered silicon crystal with total concentration of t-defects of 3·10^19 cm^−3, compensated by shallow hydrogen-like donors. The ratios of donor concentration to t-defect concentration (compensation ratios) are 0.25, 0.5, and 0.75. An electron localization radius on the negatively charged t-defect is assumed to be equal to an average distance between t-defects including donors. The calculated value of the dark hopping electrical conductivity is consistent with the known experimental data. A negative DC photoconduction at γ > α is predicted, due to a decrease in the concentration of electrons hopping via states (-1), (0) and (0), (+1).

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Reversible changes in temperature dependence of electric conductivity of hydrogenated amorphous silicon caused by proton irradiation

Cited by 3 publications

References 32 publications

Single‐Side Heterojunction Solar Cell with Microcrystalline Silicon Oxide Emitter and Diffused Back Surface Field

Single‐Side Heterojunction Solar Cell with Microcrystalline Silicon Oxide Emitter and Diffused Back Surface Field

Effect of Pressure on Bonding Environment and Carrier Transport of a-Si:H Thin Films Deposited Using 27.12 MHz Assisted PECVD Process

DC hopping photoconductivity via three-charge-state point defects in partially disordered semiconductors

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