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Impedance characteristics under different voltages of n-β-FeSi2/p-Si heterojunctions constructed via facing target sputtering
(2023-10-01)
Borwornpornmetee, Nattakorn
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Chaleawpong, Rawiwan
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Charoenyuenyao, Peerasil
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Nopparuchikun, Adison
;
Paosawatyanyong, Boonchoat
Utilizing a substrate temperature of 600 °C, n-semiconducting iron disilicide (β-FeSi<inf>2</inf>)/p-silicon heterojunctions have been constructed with direct-current sputtering and a couple of facing FeSi<inf>2</inf> targets. The impedance examination was carried out under a voltage ranging from −1 V to 1 V. Each complex impedance arch unveiled only one arc with its center beneath the real axis. Elevated voltage facilitates a reduction in the semicircle size. Based on the simulated equivalent circuit model, the heterojunctions possessed high parallel resistance and a constant phase element (CPE) at the grain boundary, raising the V. The CPE for the grain, grain boundary, and junction implied behavior close to the ideal capacitor. The dielectric loss tangent results indicated that the heterojunctions exhibited leakage behavior. From the alternating-current conductivity plots, the plateau and dispersion areas were revealed at low and high frequencies, respectively. The direct-current conductivity was 9.49 × 10−3 S cm−1 at −1 V and elevated to 8.87 × 10−2 S cm−1 at 1 V, due to the augmented charge carriers. Jonscher's power law fitting exposed that the constructed heterojunction exhibited short-range hopping within the boundary of the neighborhood.
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Reverse bias dependent impedance and dielectric properties of Al/n-NC FeSi2/p-Si/Pd heterostructures formed by facing-targets sputtering
(2022-08-01)
Borwornpornmetee, Nattakorn
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Chaleawpong, Rawiwan
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Charoenyuenyao, Peerasil
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Nopparuchikun, Adison
;
Paosawatyanyong, Boonchoat
Al/n-NC FeSi<inf>2</inf>/p-Si/Pd heterostructures were formed by facing-targets sputtering. From the dark J-V results, the device showed rectifying action with leakage current. In this work, impedance spectroscopy was employed to study the electrochemical characteristics of the heterostructures, which were inspected within a frequency (f) range from 20 Hz to 2 MHz. The range of the biased voltage (V) was −1 V to 0 V. All plots of real and imaginary impedances possessed single semi-circular arcs for all bias V values. The relaxation time was 2.00 μs at −1 V, and it became faster at 0 V with 0.42 μs. The equivalent circuit for the heterostructures consisted of series resistance (R<inf>s</inf>) combined with three sets of shunt circuits of resistance (R<inf>p</inf>) and a constant phase element (CPE), representing grain, grain boundary, and junction, respectively. The simulated R<inf>s</inf> and R<inf>p</inf> values decreased, while all CPE values increased as the biased V increased. For the dielectric properties, the real permittivity (ε′) values of 86.70 at 0 V and 20.22 at −1 V were disclosed at 100 Hz; all ε′ values decreased as the f value was increased. The loss tangent revealed to be very high due to dielectric loss being much higher than ε′ values, indicating the device to be leaky. The alternating conductivities plotted against f started at a low level in low f zones and grew exponentially when f reached higher values for all V values. Direct current conductivity was observed at 1.66 × 10−4 S m−1 at 0 V, which reduced to 2.67 × 10−5 S m−1 at −1 V. The dimensionless exponent of the conductivity results was higher than 1, indicating the hopping movement within the local site.
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Production of p-Type Si/n-Type β-FeSi2 Heterojunctions Using Facing-Targets Direct-Current Sputtering and Evaluation of Their Resistance and Interface State Density
(2018-10-24)
Chaleawpong, Rawiwan
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Promros, Nathaporn
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Charoenyuenyao, Peerasil
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Nopparuchikun, Adison
;
Sittimart, Phongsaphak
Without a post-annealing procedure, the β-FeSi<inf>2</inf> thin films are epitaxially grown on Si(111) wafer substrates via facing-targets direct-current sputtering. During epitaxial growth, the temperature for heating of substrates is maintained at 600 °C. The resultant p-type Si/n-type β-FeSi<inf>2</inf> heterojunctions are produced. At room temperature, a large leakage current under an applied reverse bias voltage together with a small photo-detective performance is observed from the measured dark and irradiated current density–voltage curves of the created heterojunctions. Both of the conductance–voltage (G/ω–V) and capacitance–voltage (C–V) measurements at different frequencies (f) in the range of 5 kHz–1 MHz are performed in the dark at room temperature. The interface state density (N<inf>ss</inf>) and series resistance (R<inf>s</inf>) in the created p-type Si/n-type β-FeSi<inf>2</inf> heterojunctions are computed and analyzed from the measured C–V–f and G/ω–V–f curves. N<inf>ss</inf> is found to be 3.48 × 1012 eV−1 cm−2 at 5 kHz and decreased to 4.68 × 1011 eV−1 cm−2 at 1 MHz. Moreover, the values of R<inf>s</inf> at zero bias are 2.21 kΩ at 5 kHz and 13.66 Ω at 1 MHz. These results review the presence of N<inf>ss</inf> and R<inf>s</inf> in the created heterojunctions, and they can be the cause to degrade the heterojunction performance.
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Characterization of junction parameters in n-type nanocrystalline iron disilicide/intrinsic ultrananocrystalline diamond/amorphous carbon composite/p-type silicon heterojunctions
(2018-01-01)
Sittimart, Phongsaphak
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Nopparuchikun, Adison
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Onsee, Peeradon
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Duangrawa, Asanlaya
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Teakchaicum, Sakmongkon
The current density-voltage curves of n-type nanocrystalline iron disilicide/intrinsic ultrananocrystalline diamond/p-type silicon heterojunctions were measured and analyzed at different temperatures. Based on computation using TE theory, the ideality factor values were 1.12 at 300 K and 5.44 at 80 K. The barrier height values were 0.69 eV at 300 K and 0.20 eV at 80 K. These parameters are in agreement with those computed using Chueng's and Norde's methods. The series resistance (R<inf>s</inf>) computed by Chueng's method were 300.88 Ω at 300 K and 4.29 MΩ at 80 K. These R<inf>s</inf> values are equal to those computed using Norde's method.
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Interface-state density estimation of n-type nanocrystalline FeSi2/p-type Si heterojunctions fabricated by pulsed laser deposition
(2017-09-01)
Nopparuchikun, Adison
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Promros, Nathaporn
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Sittimart, Phongsaphak
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Onsee, Peeradon
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Duangrawa, Asanlaya
By utilizing pulsed laser deposition (PLD), heterojunctions comprised of n-type nanocrystalline (NC) FeSi<inf>2</inf>/ thin films and p-type Si substrates were fabricated at room temperature in this study. Both dark and illuminated current density-voltage (J-V ) curves for the heterojunctions were measured and analyzed at room temperature. The heterojunctions demonstrated a large reverse leakage current as well as a weak near-infrared light response. Based on the analysis of the dark forward J-V curves, at the V value ≤ 0.2 V, we show that a carrier recombination process was governed at the heterojunction interface. When the V value was > 0.2 V, the probable mechanism of carrier transportation was a space-charge limitedcurrent process. Both the measurement and analysis for capacitance-voltage-frequency (C-V-f ) and conductance-voltage-frequency (G-V-f ) curves were performed in the applied frequency ( f ) range of 50 kHz-2 MHz at room temperature. From the C-V-f and G-V-f curves, the density of interface states (Nss) for the heterojunctions was computed by using the Hill-Coleman method. The Nss values were 9.19 × 1012 eV-1 cm-2 at 2 MHz and 3.15 × 1014 eV-1 cm-2 at 50 kHz, which proved the existence of interface states at the heterojunction interface. These interface states are the probable cause of the degraded electrical performance in the heterojunctions.
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Carrier transportation properties and series resistance of n-type β-FeSi2/p-type Si heterojunctions fabricated by RF magnetron sputtering
(2017-06-01)
Nopparuchikun, Adison
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Promros, Nathaporn
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Teakchaicum, Sakmongkon
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Onsee, Peeradon
;
Duangrawa, Asanlaya
Heterojunctions composed of n-type β-FeSi<inf>2</inf> thin films and p-type Si(111) substrates were formed by radio frequency magnetron sputtering at an Ar pressure of 2.66 × 10−1 Pa at a substrate temperature of 560 °C. The current density–voltage (J–V) curves of the heterojunctions measured in the dark and under illumination at room temperature showed a large leakage current under reverse bias conditions and a weak response to near-infrared (NIR) light irradiation. From the results of the analysis of dark forward J–V curves, the dominant carrier transport mechanisms at V ≤ 0.15 V and V > 0.15 V were considered a recombination process and a space-charge-limited current process, respectively. Both capacitance–voltage and conductance–voltage characteristics at room temperature were measured and analyzed as a function of applied frequency (f) ranging from 20 kHz to 2 MHz in order to estimate the series resistance (R<inf>s</inf>) by the Nicollian–Brews method. R<inf>s</inf> was estimated as 77.79 Ω at 20 kHz. It decreased to 14.16 Ω at 2 MHz, which is expected because the charges at the interface states cannot follow the AC signal at high f values.
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Carrier transportation properties and series resistance of n-type β-FeSi2/p-type Si heterojunctions fabricated by RF magnetron sputtering
(2017-06-01)
Nopparuchikun, Adison
;
Promros, Nathaporn
;
Teakchaicum, Sakmongkon
;
Onsee, Peeradon
;
Duangrawa, Asanlaya
Heterojunctions composed of n-type β-FeSi<inf>2</inf> thin films and Ρ-type Si(111) substrates were formed by radio frequency magnetron sputtering at an Ar pressure of 2.66 x10<inf>-1</inf> Pa at a substrate temperature of 560 °C. The current density-voltage (J-V) curves of the heterojunctions measured in the dark and under illumination at room temperature showed a large leakage current under reverse bias conditions and a weak response to nearinfrared (NIR) light irradiation. From the results of the analysis of dark forward J-V curves, the dominant carrier transport mechanisms at V : 0.15V and V > 0.15V were considered a recombination process and a space-charge-limited current process, respectively. Both capacitance-voltage and conductance-voltage characteristics at room temperature were measured and analyzed as a function of applied frequency ( f ) ranging from 20 kHz to 2MHz in order to estimate the series resistance (Rs) by the Nicollian-Brews method. Rs was estimated as 77.79Ω at 20 kHz. It decreased to 14.16Ω at 2 MHz, which is expected because the charges at the interface states cannot follow the AC signal at high f values.
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Computation of Heterojunction Parameters at Low Temperatures in Heterojunctions Comprised of n-Type β -FeSi2 Thin Films and p-Type Si(111) Substrates Grown by Radio Frequency Magnetron Sputtering
(2017-01-01)
Sittimart, Phongsaphak
;
Nopparuchikun, Adison
;
Promros, Nathaporn
In this study, n-type β-FeSi<inf>2</inf>/p-type Si heterojunctions, inside which n-type β-FeSi<inf>2</inf> films were epitaxially grown on p-type Si(111) substrates, were created using radio frequency magnetron sputtering at a substrate temperature of 560°C and Ar pressure of 2.66×10-1 Pa. The heterojunctions were measured for forward and reverse dark current density-voltage curves as a function of temperature ranging from 300 down to 20 K for computation of heterojunction parameters using the thermionic emission (TE) theory and Cheung's and Norde's methods. Computation using the TE theory showed that the values of ideality factor (n) were 1.71 at 300 K and 16.83 at 20 K, while the barrier height (φb) values were 0.59 eV at 300 K and 0.06 eV at 20 K. Both of the n and φb values computed using the TE theory were in agreement with those computed using Cheung's and Norde's methods. The values of series resistance (Rs) computed at 300 K and 20 K by Norde's method were 10.93 Ω and 0.15 MΩ, respectively, which agreed with the Rs values found through computation by Cheung's method. The dramatic increment of Rs value at low temperatures was likely attributable to the increment of n value at low temperatures.

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