This review is devoted to the analysis of the problems related to fabrication of the Si porous layers. The review was motivated by a great interest to Si-based porous materials from nano- to macro-scale for various applications in electronics, optoelectronics, photonics, chemical sensors, biosensors, etc. The peculiarities of the silicon porosification and the principles of preparing porous layers are considered in the present article. Various methods used for Si porosification such as chemical stain etching, chemical vapor etching, laser-induced etching, metal-assisted etching, spark processing and reactive ion (plasma) etching were analyzed. However, the main attention was focused on electrochemical porosification of Si. The review discusses in detail the influence of parameters such as electrolyte composition and pH, current density, etching time, temperature, wafer doping and orientation, lighting, magnetic field, and ultrasonic agitation on the process of Si porosification. It was shown that the stru...

Silicon Porosification: State of the Art

Mechanistic understanding of the reactions of small molecules containing C, N and O with Si surfaces is not only fundamentally interesting but also practically important to the development of SiC, SiN, SiO, SiCN and diamond thin films. This article reviews the recent experimental and theoretical work on the reactions of a dozen of [C, N, O]-containing molecules with single-crystal surfaces of Si, including N precursors (ammonia (NH 3 ), hydrazine (N 2 H 4 ) and hydrazoic acid (HN 3 )), CO-containing molecules (carbon monoxide (CO), formaldehyde (CH 2 O), acetaldehyde (CH 3 CHO), formic acid (HCOOH), methanol (CH 3 OH) and ketene (CH 2 CO)), CN-containing molecules (hydrogen cyanide (HCN), cyanogen (C 2 N 2 ), acetonitrile (CH 3 CN) and methylhydrazine (CH 3 N 2 H 3 )), a CNO-containing molecule (formamide (NH 2 CHO)) and some aromatic heterocyclic compounds (pyrrole (C 4 H 5 N), thiophene (C 4 H 4 S), furan (C 4 H 4 O), pyridine (C 5 H 5 N), pyrazine (C 4 H 4 N 2 ) and s -triazine (C 3 H 3 N 3 )).

Reactions of some C,N,O -containing molecules with Si surfaces: experimental and theoretical studies

The electrical characteristics of Sn/methyl-red/p-type Si/Al contacts

Single crystals of layered transition-metal dichalcogenide compounds of ${\text{ZrS}}_{x}{\text{Se}}_{2\ensuremath{-}x}$ with composition $0\ensuremath{\le}x\ensuremath{\le}2$ were grown by the chemical-vapor-transport technique and characterized with the help of different methods. Indirect gap transitions with remarkably high values of the absorption coefficient $\ensuremath{\alpha}$ $(h\ensuremath{\nu})$ and the energy-gap values have been extracted from the optical-absorption measurements. An approximate linear dependence of the band gaps on the composition parameter $x$ has been observed, qualifying them to become promising candidates for band gap engineering. The range of the obtained band gaps, which varies from 1.18 eV for ${\text{ZrSe}}_{2}$ to 1.7 eV for ${\text{ZrS}}_{2}$, is suitable for photovoltaic applications in both single- and multiple-junction cells. Additionally, a significant absorption-coefficient tail near the fundamental absorption edge is discussed, which is found to obey the Urbach rule.

Growth and band gap determination of the ZrS x Se 2-x single crystal series

The nonpolymeric organic compound (pyronine-B)/p-type silicon/Sn contact barrier devices

A metallic polypyrrole film has been formed on a p-type Si substrate by means of an anodization process An investigation of the formed polymer/pSi Schottky diodes has been made The polypyrrole polymer provides a good rectifying contact to the p-Si semiconductor The current-voltage (barrier height Φb0 = 084 eV) and capacitance-voltage (Φb0 = 094 eV) characteristics of the devices are significantly improved with increasing Φb0 and decreasing the ideality factor (n = 120) after a polymer melt processing step These values of Φb0 are significantly larger than those of conventional Schottky diodes Furthermore this study shows that owing to its room temperature processing the high barrier-metallic polypyrrole/pSi structures can be useful for deep level characterisation of p-Si

High barrier metallic polymer/p-type silicon schottky diodes

Optical absorption spectra of TlInS2 single crystals were investigated in the temperature range of 10–340 K. The exponentially increasing absorption tails were explained as Urbach tails. TlInS2 single crystals exhibited five different convergent groups of lines ln α(E,T) having different convergence points of E0 and α0 between 120 and 340 K. Characteristic Urbach’s parameters such as steepness parameter [σ(T)], Urbach’s energy [Eu(T)], and effective phonon energy (hνp) were obtained as a function of temperature. σ(T) and Eu(T) exhibited a number of jump-like trends at the identified temperature regions. Jump-like changes of σ(T) and Eu(T) were explained to be due to the phase transitions (PTs) and contributions of electron–(exciton)–phonon interaction caused by exciton dissociation. The temperature dependence of the band gap (BG) exhibited six clearly distinct regions and differs from the temperature dependent BG behavior of known semiconductors. Absorption edge and band gap anomalies in TlInS2 samples at...

H Efeoǧlu

Papers

High barrier metallic polymer/p-type silicon schottky diodes

Influence of temperature and phase transitions on the Urbach’s tails of absorption spectra for TlInS2 single crystals

Characteristics of metallic polymer and Au Schottky contacts on cleaved surfaces of InSe(:Er)