Electrical performance of conducting polymer (SPAN) grown on GaAs with different substrate orientations

Abstract

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 ...

Electrical Properties of Sulfonated Polyaniline Thin Film Grown on Different GaAs Substrates

“…It is to be noted that the higher rectification value for SPAN/(311)B n-type GaAs is considered to be an indication that the interface charge is at the lowest point between the SPAN and (311)B n-type GaAs planes. The rectification values that have been recorded by Jameel et al [24] for the samples with the SPAN thickness of 200 nm are not as high as the ones obtained in this study, as exhibited in Table 1. Therefore, the devices of the present study demonstrate better electrical properties because of the reduction of the thickness of conducting polymer (SPAN) from 200 to 120 nm.…”

“…SPAN thin films were grown utilizing the same technique as reported by Jameel et al [24]. Briefly, n-type silicon-doped (100), (311)A, and (311)B GaAs substrates with a silicon concentration of 2 × 10 18 cm −3 were utilized to grow the SPAN thin films.…”

“…We note that SPAN (120 nm)/(311)B n-type GaAs samples illustrated better electrical properties than the ones created on the conventional (100) and high index (311)A n-type GaAs substrates. In addition, it is important to mention that the electrical characteristics of our SPAN (120 nm)/(311)B GaAs devices are better than the SPAN samples with a thickness of 200 nm grown on (100), (311)A and (311)B n-GaAs substrates [24]. Therefore, the SPAN thin film with a thickness of 120 nm fabricated on (311)B n-GaAs plane can be considered as the strongest candidate to enhance efficiencies of such organic/inorganic hybrid.…”

“…Moreover, SPAN forms ohmic contacts with metals such as Ag, Cu, and Al used in microelectronic applications [6]. SPAN with a thickness of 200 nm has been grown successfully on GaAs substrates depending on the applications [24]. Much research has focused on the devices based on the low index of GaAs such as a (100) plane.…”

“…This conduct is effectively described based on the thermionic emission with a Gaussian distribution of the barrier height [30]. Additionally, Jameel et al [24] pointed out that the SPAN (200 nm)/(311)B n-type GaAs samples showed better electrical properties than SPAN (200 nm)/(100) n-type GaAs and SPAN (200 nm)/ (311)A GaAs hybrid devices.…”