Effect of series resistance on the electrical characteristics and interface state energy distributions of Sn/p-Si (MS) Schottky diodes

In this study, electrical characteristics of the Sn/p-type Si (MS) Schottky diodes have been investigated by current-voltage (I-V) and capacitance-voltage (C-V) measurements at room temperature. The barrier height obtained from C-V measurement is higher than obtained from I-V measurement and this discrepancy can be explained by introducing a spatial distribution of barrier heights due to barrier height inhomogeneities, which are available at the nanostructure Sn/p-Si interface. A modified Norde’s function combined with conventional forward I-V method was used to extract the parameters including barrier height (Φ_b) and the series resistance (R_S). The barrier height and series resistance obtained from Norde’s function was compared with those from Cheung functions. In addition, the interface-state density (N_SS) as a function of energy distribution (E_SS-E_V) was extracted from the forward-bias I-V measurements by taking into account the bias dependence of the effective barrier height (Φ_b) and series resistance (R_S) for the Schottky diodes. While the interface-state density (N_SS) calculated without taking into account series resistance (R_S) has increased exponentially with bias from 4.235 × 10¹² cm⁻²eV⁻¹ in (E_SS - 0.62) eV to 2.371 × 10¹³ cm⁻²eV⁻¹ in (E_SS - 0.39) eV of p-Si, the N_SS obtained taking into account the series resistance has increased exponentially with bias from of 4.235 × 10¹² to 1.671 × 10¹³ cm⁻²eV⁻¹ in the same interval. This behaviour is attributed to the passivation of the p-doped Si surface with the presence of thin interfacial insulator layer between the metal and semiconductor.     

Big Third-order Nonlinear Optical Properties of Two Poly[ (3-alkylthiophene-2, 5-diyl ) - ( benzylidenequinomethane-2, 5-diyi ) ] Derivatives

Two novel poly[(3-alkylthiophene-2,5-diyl)- (benzylidenequinomethane-2,5-diyl)s] derivatives,poly[ (3-butylthiophene-2,5-diyl)- ( p-N, N-dimethylamino) benzylidenequinomethane-2, 5-diyl) ] (PBTDMABQ)and poly [( 3-octylthiophene2, 5-diyl ) -( p-N, N-dimethylamino ) benzylidenequinomethane-2, 5-diyl )](POTDMABQ), were synthesized. The band gaps of the two polymers are calculated as 1. 75 eV for PBTDMABQ and 1.69 eV for POTDMABQ, respectively. The homogenous films of the two polymers were prepared and their third-order nonlinear optical properties were studied by the backward degenerate four-wave mixing at 532 nm. By using the relative measurement technique, the third-order nonlinear optical susceptibilities of PBTDMABQ and POTDMABQ are calculated as 5. 62 × 10-9 and 1. 22 × 10-8 ESU,respectively. It is found that substituted alky groups have strong effects on the band gap and nonlinear opticalproperties of the two polymers. The relatively big third-order nonlinear optical susceptibilities and small band gap of POTDMABQ resulted mainly from the longer alkyl with strong electron-donating ability can enhance the delocation degree of conjugated π electronics.     

Optical,electrical and photovoltaic properties of thermally evaporated 3-amino-2-[(2-nitrophenyl)diazinyl]-3-(piperidin-1-yl)acrylonitrile thin films

Thin films with various thickness of 3-amino-2-[(2-nitrophenyl)diazinyl]-3-(piperidin-1-yl)acrylonitrile (ANPA) were produced by conventional thermal evaporation. The dependence of the optical, electrical, and photovoltaic properties on the film thickness was investigated. X-ray diffraction showed that the films have an amorphous structure. The optical properties were investigated in terms of transmittance and reflectance in the spectral range 200–2500 nm. Spectral distribution analysis of the absorption coefficient revealed that the films have an indirect allowed electronic interband transition. The optical bandgap decreased from 2.47 to 2.1 eV for an increase in film thickness from 105 to 265 nm. The direct current electrical conductivity of the films was measured for sandwich-structured samples as a function of the heating temperature and film thickness. The films exhibited semiconductor behavior and electrical conduction was attributed to hopping of charge carriers in localized states. ANPA films of differing thickness were deposited on p-type Si single-crystal substrates. The influence of film thickness on the electrical and photovoltaic parameters of Au/ANPA/p-Si/Al heterojunction solar cells was investigated.     

Reactions of GaX3 (x  br,i) with AS(SiMe3)3; crystal structures of I3Ga · as(SiMe3)3 and [I2GaAS(sime3)2]2

Reactions of GaX₃ (X ? Br, I) with As(SiMe₃)₃ in 1:1 and 2:1 mole ratios were investigated. For the latter reactant stoichiometry, substances having the empirical formulae AsBr₃Ga₂ (1) and Asl₃Ga₂ (2), the analogues of the previously reported single-source GaAs precursor (AsCl₃Ga₂)_n, were isolated as yellow isolated as yellow insoluble powders. Low-temperature reactions in a 1:1 mole ratio resulted in the isolation of the adducts Br₃Ga.As(SiMe₃)₃ (3) and I₃Ga.As(SiMe₃)₃ (4). On the other hand, at room temperature the GaBr₃ reaction resulted in a complex mixture from which no characterizable compounds were isolated, whereas the Gal₃ reaction afforded the crystalline compound [I₂GaAs(SiMe₃)₂]₂ (5). The structures of 4 and 5 were elucidated by complete single-crystal X-ray analysis (crystal data: 4, monoclinic, space group P2₁/c, a = 16.497(2) Å, b = 9.629(1) Å, c = 16.658(2) Å, β = 113.21(1)°, V = 2432(1) ų, Z = 4; 5, orthorhombic, space group Pbca, a = 14.279(2) Å, b = 17.509(2) Å, c = 13.818(2), Å, V = 3455(1) ų, Z = 4).