Simulation and Experimental Studies of Illumination Effects on the Current Transport of Nitridated GaAs Schottky Diode

Semiconductors - In this paper, we studied the electrical characteristic of Schottky diodes based on gold contact on nitridated GaAs substrates. The used (100) GaAs substrate is n-type with...     

Further insights into the photodegradation of poly(3-hexylthiophene) by means of X-ray photoelectron spectroscopy

X-ray photoelectron spectroscopy (XPS) was used to monitor the chemical changes resulting from irradiation (> 295 nm) in air of poly(3-hexylthiophene) (P3HT), polymer which is a good candidate for photovoltaic applications. The formation of carbonyl moieties and the stepwise oxidation of sulphur atoms were characterised. The oxidation and the cleavage of the hexyl side-chain was monitored. It is also shown that sulfur was first converted into sulfoxides, then into sulfones and finally into sulfinate esters. The formation of these ultimate degradation products provoked a disruption of π-conjugation in P3HT, leading to diminished visible absorbance. Based on these results, a mechanism of P3HT photooxidation is proposed. Comparison of XPS data with previously reported infrared and UV-visible spectral analysis showed that the information provided by these techniques is completely consistent.     

Electrical characterization of alumina layers deposited by evaporation cell on Si and restructured InP substrates

In the fast electronic area, studies on InP metal—insulator—semiconductor (MIS) devices have wide interest. Effectively, InP presents a considerable interest due to its high mobility and large bandgap for high speed MIS devices. However, the InP surface must be treated and well passivated before the deposition of insulator. We show that the InSb buffer layer can reduce the phosphorus atom migration and the defects at the interface. After the elaboration of Al₂O₃/Si, Al₂O₃/InP and Al₂O₃:InSb/InP structures, we have studied and characterized electrically the alumina—semiconductor systems. Thus, a mercury probe was used as a temporary gate contact. In the Al₂O₃:InSb/InP structure, the electrical C–V characteristics plotted at 1 MHz give, in the depletion region, a more important slope of the curves. The obtained results show clearly the reduction of the defects, dangling bonds and consequently the state density has been decreased by 50% compared to the InP protected by an InSb buffer layer and no treated surfaces. Then, the interfacial state density N_SS is evaluated as 4 × 10¹¹ eV⁻¹ cm⁻².     

A study of InP(100) surface passivation by antimony deposition

InP(100) is a promising substrate for microelectronic and optoelectronic devices due to its high mobility. Sb atomic condensation induces the formation of some InSb overlayers that produce passivation of the surface. First steps of the mechanism have been studied at atomic scale using synchrotron radiation. The process of InSb formation is due to a 3D-2D phase transformation. In this work we also point out the effect of the sample heating. Results are in good agreement with previous ones obtained by Auger electron spectroscopy (AES) and electron energy loss spectroscopy (EELS). We have obtained a good stabilization of the surface with respect to any prolonged heating up to 450 °C. The size of the In or Sb clusters decreases with temperature: the InSb monolayer becomes almost stoichiometric at 450 °C. The substrate has also a good quality for an optimum behavior of electronic components (L. Bideux, B. Gruzza, A. Porte and H. Robert, Surf. Interface Anal., 20 (1993) 803–807).