This article reports the effect of n-type GaAs substrate orientation, namely (100), IntroductionEssentially conducting polymers, such as polyaniline (PANI), sulfonated polyaniline (SPAN), poly(p-phenylene-vinylene), polypyrrole, polyacetylene, polythiophene, etc., are promising semiconductors materials with confirmed technological potential due to their unique optical and electrical properties [1]. Among the family of organic semiconductors, the semiconducting polymers have attracted the most attention for applications in electronic and optoelectronic devices, particularly due to their exceptional electrical properties and easy synthesis [2][3][4]. As a result, this category of polymers has been used in several applications such as organic light emitting diodes (OLEDs) [5,6], solar cells [7,8] As it is well known, the crystallographic orientation of the substrate has a significant effect on incorporation of impurities and defects and consequently on optical and electronic properties of III-V materials [28]. The ideality factor n and barrier height (BH) as well as the electrical characteristics are fundamental parameters of a Schottky barrier diode (SBD) and these give an indication about the quality of the Schottky interface. The SBD parameters must be determined over a broad range of temperatures because the analysis of the current-voltage (I-V) characteristics of the SBD measured only at room temperature does not provide accurate information about the conduction mechanism and the barrier nature created at metal semiconductor interface in order to understand these phenomena and determine precisely the parameters of the Schottky diodes. Chand et al. [29] and Hardikar et al.[30] analysed the experimental currentvoltage data which revealed that there is an increase in the ideality factor and a decrease in the zero-bias barrier height with decreasing temperature. Consequently, the ideality factor and the barrier height established from forward I-V characteristics are found to be temperature dependent. This confirms that the Schottky barrier height is inhomogeneous in nature at the interface. This behaviour has been successfully described on the basis of the thermionic emission mechanism with Gaussian distribution of the barrier heightTo fabricate a hybrid organic/inorganic semiconductor heterojunction device with the aim to obtain specific optical and electrical properties on the bases of their doping levels, a thin organic film is deposited onto the surface of a conventional inorganic semiconductor substrate. This can be done by simple and inexpensive methods such as 4 spin coating used for thin film deposition at room temperature. Recently, a new technique of SPAN films preparation has been developed by Yang et al. [32].In this paper, we report on the fabrication and electrical characterization of Au/SPAN/GaAs heterojunctions grown on three different substrate orientations, namely n-type GaAs (100), (311)A and (311)B. We have investigated the effect of the substrate orientation on the heterojunction parameters ...

a b s t r a c tThis work reports the effect of gamma (g-) irradiation on dilute GaAsN with nitrogen concentrations ranging from 0.2 to 1.2% with post-irradiation stability using CurrenteVoltage (IeV) and Deep Level Transient Spectroscopy (DLTS) measurements in the temperature range from 10 K to 450 K. The IeV results indicate that the irradiation effect was more pronounced in the samples with nitrogen concentration of 0.4%. Additionally, the irradiated samples showed an ideality factor higher than the as-grown samples. On the other hand, for temperatures above 265 K the barrier height of the irradiated samples with 0.8% nitrogen is higher than the as-grown samples. The DLTS measurements revealed that after irradiation the number of traps either decreased remained constant, or new traps are created depending on the concentration of nitrogen. For samples with N ¼ 0.2% e 0.4% the number of traps after irradiation decreased, whereas for samples with N ¼ 0.8% À 1.2 % the number of traps remained the same. However, the properties of some traps such as capture cross-sections and density increased by about 2 orders of magnitude. The origin of the defects present before and after irradiation are discussed and correlated.

Please cite this article in press as: D.A. Jameel, et al., High-performance organic/inorganic hybrid heterojunction based on Gallium Arsenide (GaAs) substrates and a conjugated polymer, Appl. Surf. Sci. (2015), http://dx. a b s t r a c tIn this paper, we present an extensive study of the electrical properties of organic-inorganic hybrid heterojunctions. Polyaniline (PANI) thin films were deposited by a very simple technique on (1 0 0) and (3 1 1)B n-type Gallium Arsenide (GaAs) substrates to fabricate hybrid devices with excellent electrical properties. The hybrid devices were electrically characterized using current-voltage (I-V), capacitance-voltage (C-V) and deep level transient spectroscopy (DLTS) measurements in the temperature range 20-440 K. The analysis of I-V characteristics based on the thermionic emission mechanism has shown a decrease of the barrier height and an increase of the ideality factor at lower temperatures for both hybrid devices. The interface states were analyzed by series resistance obtained using the C-G-V methods. The interface state density (D it ) of PANI/(1 0 0) GaAs devices is approximately one order of magnitude higher than that of PANI/(3 1 1)B GaAs devices. This behaviour is attributed to the effect of crystallographic orientation of the substrates, and was confirmed by DLTS results as well. Additionally, the devices show excellent air stability, with rectification ratio values almost unaltered after two years of storage under ambient conditions, making the polyaniline an interesting conductor polymer for future devices applications.