共查询到20条相似文献,搜索用时 31 毫秒
1.
R. M. Sardarly O. A. Samedov A. P. Abdullayev F. T. Salmanov O. Z. Alekperov E. K. Huseynov N. A. Aliyeva 《Semiconductors》2011,45(11):1387-1390
The temperature dependences of the conductivity σ(T) and the switching and memory effects in one-dimensional TlInSe2 and TlInTe2 single crystals have been studied. A specific feature is found in the dependence σ(T) above 333 K, which is related to the transition of crystals to the state with superionic conductivity. It is suggested that
the ion conductivity is caused by the diffusion of Tl+ ions over vacancies in the thallium sublattice between (In3+Te22−)− and (In3+Se22−)− nanochains (nanorods). S-type switching and memory effects are revealed in TlInSe2 and TlInTe2 crystals, as well as voltage oscillations in the range of negative differential resistance. It is suggested that the switching
effect and voltage oscillations are related to the transition of crystals to the superionic state, which is accompanied by
“melting” of the Tl sublattice. The effect of electric-field-induced transition of TlInSe2 and TlInTe2 crystals to the superionic state is found. 相似文献
2.
Te-doped Mg2Si (Mg2Si:Te
m
, m = 0, 0.01, 0.02, 0.03, 0.05) alloys were synthesized by a solid-state reaction and mechanical alloying. The electronic transport
properties (Hall coefficient, carrier concentration, and mobility) and thermoelectric properties (Seebeck coefficient, electrical
conductivity, thermal conductivity, and figure of merit) were examined. Mg2Si was synthesized successfully by a solid-state reaction at 673 K for 6 h, and Te-doped Mg2Si powders were obtained by mechanical alloying for 24 h. The alloys were fully consolidated by hot-pressing at 1073 K for
1 h. All the Mg2Si:Te
m
samples showed n-type conduction, indicating that the electrical conduction is due mainly to electrons. The electrical conductivity increased
and the absolute value of the Seebeck coefficient decreased with increasing Te content, because Te doping increased the electron
concentration considerably from 1016 cm−3 to 1018 cm−3. The thermal conductivity did not change significantly on Te doping, due to the much larger contribution of lattice thermal
conductivity over the electronic thermal conductivity. Thermal conduction in Te-doped Mg2Si was due primarily to lattice vibrations (phonons). The thermoelectric figure of merit of intrinsic Mg2Si was improved by Te doping. 相似文献
3.
O. G. Grushka S. M. Chupyra O. M. Myslyuk S. V. Bilichuk I. I. Zabolotsky 《Semiconductors》2011,45(1):49-51
The effect of electric field and temperature on the conductivity of bulk Hg3In2Te6 crystals is investigated. It is shown that the I–V characteristics in high electric fields are of the S type with the effect of switching into a low-resistance state. The critical voltage of transition from the Ohm law to the
exponential dependence of the current (I) on the voltage (U) and the threshold voltage of transition into the region of negative differential resistance dU/dI = s< 0 linearly depend on the sample thickness. The activation energies of conductivity in low and high electric fields are
determined. It is established that the superlinear portion of the I–V characteristic with dU/dI > 0 is described by the dependence of the type I = I
0 exp(U/U
0) and caused by the electron transitions from the local centers with the energy level E
t = 0.19 eV. 相似文献
4.
Chunya Wu Zhiguo Meng Shuyun Zhao Shaozhen Xiong Man Wong Hoi Sing Kwok 《Journal of Electronic Materials》2007,36(9):1160-1165
By using an aqueous solution of Ni(NO3)2/NH4OH for formation of Ni media on a-Si, disk-like super-large domain metal-induced radially crystallized (S-MIRC) poly-Si was
prepared. The process requires no buffer layer deposition on a-Si. The prepared S-MIRC poly-Si has an average domain size
of up to 60 μm, highest hole Hall mobility of 27.1 cm2 V−1 s−1, and highest electron Hall mobility of 45.6 cm2 V−1 s−1. Poly-Si TFT made on super-large-domain S-MIRC poly-Si had high mobility of ~105.8 cm2 V−1 s−1, steep sub-threshold slope of ~1.0 V decade−1, high on/off state current ratio of >107 and low threshold voltage of ~ −6.9 V. A simultaneous Ni-collected and induced crystallization model is proposed to explain
the growth kinetics of S-MIRC poly-Si. 相似文献
5.
L. P. Kazakova K. D. Tsendin E. A. Lebedev D. Arsova I. A. Obukhova 《Semiconductors》2010,44(1):76-78
Charge-carrier transport in Ge20As20S60 films has been studied using the transit time method under low-injection conditions at room temperature. It was found that
drift mobilities of electrons and holes in Ge20As20S60 films are close to each other, i.e., μ
e
≈ μ
h
≈ 2 × 10−3 cm2 V−1 s−1 at T = 295 K and F = 5 × 104 V/cm. It was shown that the time dependence of the photocurrent during carrier drift and the voltage dependence of the drift
mobility allowed the use of the concept of anomalous dispersive transport. Experimental data were explained using the model
of transport controlled by carrier trapping by localized states with energy distribution near conduction and valence band
edges described by the exponential law with a characteristic energy of ∼0.05 eV. 相似文献
6.
Resonant electron scattering in p-Ag2Te at acceptor concentrations N
a < 4.2 × 1016 cm−3 has been observed in the temperature range of 50–80 K. The contribution of the resonant scattering to the temperature dependences
of the conductivity σ(T) and thermopower α0(T) has been calculated. It is shown that this contribution exceeds that of charge carrier scattering by acoustic phonons. 相似文献
7.
We report on the ultraviolet (UV) photodetection properties of a Pt contact on a sol-gel Mg0.1Zn0.9O/ZnO composite structure on a glass substrate. In the dark, the current–voltage (I–V) characteristics between the Pt and Ag contacts on the top of the ZnO film were linear while that on the Mg0.1Zn0.9O/ZnO composite film were rectifying, suggesting the formation of a Schottky diode on the latter. The ideality factor, n, and the reverse leakage current density, J
R
, of the Schottky diode were greater than 2 and 2.36 × 10−2 A cm−2 at −5 V, respectively. Under ultraviolet light, the I–V characteristics become linear. The maximum photo-to-dark current ratio observed was about 63. The composite film showed good
sensitivity to UV light with wavelengths of less than 400 nm, though the photoresponse process was found to be slow. 相似文献
8.
R. M. Sardarli O. A. Samedov A. P. Abdullayev E. K. Huseynov E. M. Qocayev F. T. Salmanov 《Semiconductors》2011,45(8):975-979
Temperature dependences of electrical conductivity σ(T) and permittivity ɛ(T) of one-dimensional (1D) TlGaTe2 single crystals are investigated. At temperatures higher than 305 K, superionic conductivity of the TlGaTe2 is observed and is related to diffusion of Tl+ ions via vacancies in the thallium sublattice between (Ga3+Te22−
− nanochains. A relaxation character of dielectric anomalies is established, which suggests the existence of electric charges
weakly bound to the crystal lattice. Upon the transition to the superionic state, relaxors in the TlGaTe2 crystals are Tl+ dipoles ((Ga3+Te22−)− chains) that arise due to melting of the thallium sublattice and hops of Tl+ ions from one localized state to another. The effect of a field-induced transition of the TlGaTe2 crystal to the superionic state is detected. 相似文献
9.
The Seebeck coefficient, electrical resistivity, and thermal conductivity of Zr3Mn4Si6 and TiMnSi2 were studied. The crystal lattices of these compounds contain relatively large open spaces, and, therefore, they have fairly
low thermal conductivities (8.26 Wm−1 K−1 and 6.63 Wm−1 K−1, respectively) at room temperature. Their dimensionless figures of merit ZT were found to be 1.92 × 10−3 (at 1200 K) and 2.76 × 10−3 (at 900 K), respectively. The good electrical conductivities and low Seebeck coefficients might possibly be due to the fact
that the distance between silicon atoms in these compounds is shorter than that in pure semiconductive silicon. 相似文献
10.
Yong Liu Yuan-Hua Lin Jinle Lan Bo-Ping Zhang Wei Xu Ce-Wen Nan Hongmin Zhu 《Journal of Electronic Materials》2011,40(5):1083-1086
Polycrystalline In2O3 ceramics co-doped with Zn and Nd were prepared by the spark plasma sintering (SPS) process, and microstructure and thermoelectric
(TE) transport properties of the ceramics were investigated. Our results indicate that co-doping with Zn2+ and Nd3+ shows a remarkable effect on the transport properties of In2O3-based ceramics. Large electrical conductivity (~130 S cm−1) and thermopower (~220 μV K−1) can be observed in these In2O3-based ceramic samples. The maximum power factor (PF) reaches 5.3 × 10−4 W m−1 K−2 at 973 K in the In1.92Nd0.04Zn0.04O3 sample, with a highest ZT of ~0.25. 相似文献
11.
B. N. Pantha R. Dahal J. Li J. Y. Lin H. X. Jiang G. Pomrenke 《Journal of Electronic Materials》2009,38(7):1132-1135
We report on the experimental investigation of the potential of InGaN alloys as thermoelectric (TE) materials. We have grown
undoped and Si-doped In0.3Ga0.7N alloys by metalorganic chemical vapor deposition and measured the Seebeck coefficient and electrical conductivity of the
grown films with the aim of maximizing the power factor (P). It was found that P decreases as electron concentration (n) increases. The maximum value for P was found to be 7.3 × 10−4 W/m K2 at 750 K in an undoped sample with corresponding values of Seebeck coefficient and electrical conductivity of 280 μV/K and 93␣(Ω cm)−1, respectively. Further enhancement in P is expected by improving the InGaN material quality and conductivity control by reducing background electron concentration. 相似文献
12.
Wei Liu Qiang Zhang Xinfeng Tang Han Li Jeff Sharp 《Journal of Electronic Materials》2011,40(5):1062-1066
Mg2(Si0.3Sn0.7)1−y
Sb
y
(0 ≤ y ≤ 0.04) solid solutions were prepared by a two-step solid-state reaction method combined with the spark plasma sintering
technique. Investigations indicate that the Sb doping amount has a significant impact on the thermoelectric properties of
Mg2(Si0.3Sn0.7)1−y
Sb
y
compounds. As the Sb fraction y increases, the electron concentration and electrical conductivity of Mg2(Si0.3Sn0.7)1−y
Sb
y
first increase and then decrease, and both reach their highest value at y = 0.025. The sample with y = 0.025, possessing the highest electrical conductivity and one of the higher Seebeck coefficient values among all the samples,
has the highest power factor, being 3.45 mW m−1 K−2 to 3.69 mW m−1 K−2 in the temperature range of 300 K to 660 K. Meanwhile, Sb doping can significantly reduce the lattice thermal conductivity
(κ
ph) of Mg2(Si0.3Sn0.7)1−y
Sb
y
due to increased point defect scattering, and κ
ph for Sb-doped samples is 10% to 20% lower than that of the nondoped sample for 300 K < T < 400 K. Mg2(Si0.3Sn0.7)0.975Sb0.025 possesses the highest power factor and one of the lower κ
ph values among all the samples, and reaches the highest ZT value: 1.0 at 640 K. 相似文献
13.
A. I. D’Souza M. G. Stapelbroek P. N. Dolan P. S. Wijewarnasuriya R. E. DeWames D. S. Smith J. C. Ehlert 《Journal of Electronic Materials》2003,32(7):633-638
The 1/f noise in photovoltaic (PV) molecular-beam epitaxy (MBE)-grown Hg1−xCdxTe double-layer planar heterostructure (DLPH) large-area detectors is a critical noise component with the potential to limit
sensitivity of the cross-track infrared sounder (CrIS) instrument. Therefore, an understanding of the origins and mechanisms
of noise currents in these PV detectors is of great importance. Excess low-frequency noise has been measured on a number of
1000-μm-diameter active-area detectors of varying “quality” (i.e., having a wide range of I-V characteristics at 78 K). The
1/f noise was measured as a function of cut-off wavelength under illuminated conditions. For short-wave infrared (SWIR) detectors
at 98 K, minimal 1/f noise was measured when the total current was dominated by diffusion with white noise spectral density
in the mid-10−15A/Hz1/2 range. For SWIR detectors dominated by other than diffusion current, the ratio, α, of the noise current in unit bandwidth
in(f = 1 Hz, Vd = −60 mV, and Δf = 1 Hz) to dark current Id(Vd = −60 mV) was αSW-d = in/Id ∼ 1 × 10−3. The SWIR detectors measured at 0 mV under illuminated conditions had median αSW-P = in/Iph ∼ 7 × 10−6. For mid-wave infrared (MWIR) detectors, αMW-d = in/Id ∼ 2 × 10−4, due to tunneling current contributions to the 1/f noise. Measurements on forty-nine 1000-μm-diameter MWIR detectors under
illuminated conditions at 98 K and −60 mV bias resulted in αMW-P = in/Iph = 4.16 ± 1.69 × 10−6. A significant point to note is that the photo-induced noise spectra are nearly identical at 0 mV and 100 mV reverse bias,
with a noise-current-to-photocurrent ratio, αMW-P, in the mid 10−6 range. For long-wave infrared (LWIR) detectors measured at 78 K, the ratio, αLW-d = in/Id ∼ 6 × 10−6, for the best performers. The majority of the LWIR detectors exhibited αLW-d on the order of 2 × 10−5. The photo-induced 1/f noise had αLW-P = in/Iph ∼ 5 × 10−6. The value of the noise-current-to-dark-current ratio, α appears to increase with increasing bandgap. It is not clear if
this is due to different current mechanisms impacting 1/f noise performance. Measurements on detectors of different bandgaps
are needed at temperatures where diffusion current is the dominant current. Excess low-frequency noise measurements made as
a function of detector reverse bias indicate 1/f noise may result primarily from the dominant current mechanism at each particular
bias. The 1/f noise was not a direct function of the applied bias. 相似文献
14.
Ternary rare-earth sulfides NdGd1+x
S3, where 0 ≤ x ≤ 0.08, were prepared by sulfurizing Ln2O3 (Ln = Nd, Gd) with CS2 gas, followed by reaction sintering. The sintered samples have full density and homogeneous compositions. The Seebeck coefficient,
electrical resistivity, and thermal conductivity were measured over the temperature range of 300 K to 950 K. All the sintered
samples exhibit a negative Seebeck coefficient. The magnitude of the Seebeck coefficient and the electrical resistivity decrease
systematically with increasing Gd content. The thermal conductivity of all the sintered samples is less than 1.9 W K−1 m−1. The highest figure of merit ZT of 0.51 was found in NdGd1.02S3 at 950 K. 相似文献
15.
Current-voltage characteristics of the In-ZnGa2Se4-In structure have been studied in the temperature range of 90–335 K. Based on the data calculated for the concentration of
three trap types in ZnGa2Se4, the values N
t
= 1.4 × 1013, 8.2 × 1012, and 2.6 × 1012 cm−3 are obtained. The contact region transparency D
k
*= 10−5, surface recombination velocity S
k
= 0.65 m/s, and carrier lifetime τ = 1.5 × 10−4 s were determined. It was found that the current transmission mechanism in electric fields weaker than 103 V/cm is caused by monopolar carrier injection. 相似文献
16.
Thermoelectric materials are attractive since they can recover waste heat directly in the form of electricity. In this study,
the thermoelectric properties of ternary rare-earth sulfides LaGd1+x
S3 (x = 0.00 to 0.03) and SmGd1+x
S3 (x = 0.00 to 0.06) were investigated over the temperature range of 300 K to 953 K. These sulfides were prepared by CS2 sulfurization, and samples were consolidated by pressure-assisted sintering to obtain dense compacts. The sintered compacts
of LaGd1+x
S3 were n-type metal-like conductors with a thermal conductivity of less than 1.7 W K−1 m−1. Their thermoelectric figure of merit ZT was improved by tuning the chemical composition (self-doping). The optimized ZT value of 0.4 was obtained in LaGd1.02S3 at 953 K. The sintered compacts of SmGd1+x
S3 were n-type hopping conductors with a thermal conductivity of less than 0.8 W K−1 m−1. Their ZT value increased significantly with temperature. In SmGd1+x
S3, the ZT value of 0.3 was attained at 953 K. 相似文献
17.
K.K. Allums M. Hlad A.P. Gerger B.P. Gila C.R. Abernathy S.J. Pearton F. Ren R. Dwivedi T.N. Fogarty R. Wilkins 《Journal of Electronic Materials》2007,36(4):519-523
Proton irradiation of Sc2O3/GaN and Sc2O3/MgO/GaN metal-oxide semiconductor diodes was performed at two energies, 10 MeV and 40 MeV, and total fluences of 5 × 109 cm−2, corresponding to 10 years in low-earth orbit. The proton damage causes a decrease in forward breakdown voltage and a flat-band
voltage shift in the capacitance-voltage characteristics, indicating a change in fixed oxide charge and damage to the dielectric.
The interface state densities after irradiation increased from 5.9 × 1011 cm−2 to 1.03 × 1012 cm−2 in Sc2O3/GaN diodes and from 2.33 × 1011 to 5.3 × 1011 cm−2 in Sc2O3/MgO/GaN diodes. Postannealing at 400°C in forming gas recovered most of the original characteristics but did increase the
interfacial roughness. 相似文献
18.
Silver doped p-type Mg2Ge thin films were grown in situ at 773 K using magnetron co-sputtering from individual high-purity Mg and Ge targets. A sacrificial
base layer of silver of various thicknesses from 4 nm to 20 nm was initially deposited onto the substrate to supply Ag atoms,
which entered the growing Mg2Ge films by thermal diffusion. The addition of silver during film growth led to increased grain size and surface microroughness.
The carrier concentration increased from 1.9 × 1018 cm−3 for undoped films to 8.8 × 1018 cm−3 for the most heavily doped films, but it did not reach saturation. Measurements in the temperature range of T = 200–650 K showed a positive Seebeck coefficient for all the films, with maximum values at temperatures between 400 K and
500 K. The highest Seebeck coefficient of the undoped film was 400 μV K−1, while it was 280 μV K−1 for the most heavily doped film at ∼400 K. The electrical conductivity increased with silver doping by a factor of approximately
10. The temperature effects on power factors for the undoped and lightly doped films were very limited, while the effects
for the heavily doped films were substantial. The power factor of the heavily doped films reached a non-optimum value of ∼10−5 W cm−1 K−2 at 700 K. 相似文献
19.
E.A. Moore Y.K. Yeo G.J. Gruen Mee-Yi Ryu R.L. Hengehold 《Journal of Electronic Materials》2010,39(1):21-28
Electrical activation studies were carried out on Si-implanted Al0.33Ga0.67N as a function of ion dose, annealing temperature, and annealing time. The samples were implanted at room temperature with
Si ions at 200 keV in doses ranging from 1 × 1014 cm−2 to 1 × 1015 cm−2, and subsequently proximity-cap annealed from 1150°C to 1350°C for 20 min to 60 min in a nitrogen environment. One hundred
percent electrical activation efficiency was obtained for Al0.33Ga0.67N samples implanted with a dose of 1 × 1015 cm−2 after annealing at either 1200°C for 40 min or at 1300°C for 20 min. The samples implanted with doses of 1 × 1014 cm−2 and 5 × 1014 cm−2 exhibited significant activations of 74% and 90% after annealing for 20 min at 1300°C and 1350°C, respectively. The mobility
increased as the annealing temperature increased from 1150°C to 1350°C, showing peak mobilities of 80 cm2/V s, 64 cm2/V s, and 61 cm2/V s for doses of 1 × 1014 cm−2, 5 × 1014 cm−2, and 1 × 1015 cm−2, respectively. Temperature-dependent Hall-effect measurements showed that most of the implanted layers were degenerately
doped. Cathodoluminescence measurements for all samples exhibited a sharp neutral donor-bound exciton peak at 4.08 eV, indicating
excellent recovery of damage caused by ion implantation. 相似文献
20.
A. O. Evwaraye 《Journal of Electronic Materials》2010,39(6):751-755
n-Type 4H-SiC bulk samples with a net doping concentration of 2.5 × 1017 cm−3 were irradiated at room temperature with 1-MeV electrons. The high doping concentration plus a reverse bias of up to −13 V
ensures high electric field in the depletion region. The dependence of the emission rate on the electric field in the depletion
region was measured using deep-level transient spectroscopy (DLTS) and double-correlation deep-level transient spectroscopy
(DDLTS). The experimental data are adequately described by the phonon-assisted tunneling model proposed by Karpus and Pere. 相似文献