I nternational Journal of Application or I nnovation in E ngineering & M anagement (I JAI E M ) Web Site: www.ijaiem.org Email: editor@ijaiem.org Volume 4, Issue 1, January 2015 ISSN 2319 - 4847 Volume 4, Issue 1, January 2015 Page 62 ABSTRACT Far infrared photoconductive detectors based on multi-wall carbon nanotubes (MWCNTs) were fabricated and their characteristics were tested. MWCNTs films deposited on porous silicon (PSi) nanosurface by dip and drop coating techniques. Two types of deposited methods were used; dip coating sand drop –by-drop methods. As well as two types of detector were fabricated one with aluminum mask and the other without, and their figures of merits were studied. The detectors were illuminated by 2.2 and 2.5 Watt from CO2 of 10.6 ฀m and tested. The surface morphology for the films is studied using AFM and SEM micrographs. The films show homogeneous distributed for CNTs on the PSi layer. The root mean square (r.m.s.) of the films surface roughness indicates a smooth surface of the synthesized films. The Raman spectrum at room temperature for MWCNTs, are dominated by the two typical lines at about 1335.4 cm -1 (D line) and 1563.2 cm -1 (G line) assigned to the disorder induced by defects and curvature in the nanotubes lattice, and to the in-plane vibration of the C–C bonds, respectively. The results reflect a good IR radiation sensitivity and photoconductive gain, while the specific detectivity was in order of 10 7 cm.Hz 1/2 /W. Key Words:- MWCNT, porous silicon, infrared, photoconductive detectors. 1. INTRODUCTION Carbon nanotubes has been a source of motivation for scientists and researchers, due to their unique mechanical [1-2], chemical and electronic properties [3-4]. Optoelectronic properties of CNTs makes them very interesting component for infrared sensors. The carbon nanotubes are a unique material that can be either semiconductor or metallic with a small band gap inversely proportional to tube diameter and with interesting optical properties. CNT mats interest for many electronic applications such as electrodes, transistors, and sensors[5,6]. Among CNTs based sensors, photosensors and especially infrared _IR_ sensors have recently attracted much attention, since CNTs exhibit wide absorbance in the infrared range.In this work, the improvement of the photoresposivity and response time of infrared photoconductive detector based on multi-walled carbon nanotubes (MWCNTs) deposited on porous silicon (PSi) layer were carried out. Porous Silicon is a network consisting of pores separated by thin columns and contains nano-meter sized silicon crystallites [7, 8] as a result; PSi is characterized by a very large internal surface. Porous silicon formed under different anodization conditions exhibits a variety of rich and complex structure with many features [9]. The physical properties of porous silicon (PSi) are fundamentally determined by the shape and diameter of PSi was discovered in 1956 by Uhlir [10]. Infrared (IR) detection has a wide range of military, homeland security, industry, biomedicine, and astronomy applications, since the blackbody radiation of humans and the atmosphere are in the IR spectrum [11]. An infrared detector is a detector that reacts to infrared (IR) radiation. The two main types of detectors are thermal and photonic (photodetectors). The thermal effects of the incident IR radiation can be followed through many temperature dependent phenomena. The response time and sensitivity of photonic detectors can be much higher, but usually these have to be cooled to cut thermal noise. The materials in these are semiconductors with narrow band gaps. Incident IR photons can cause electronic excitations [12]. 2.EXPERIMENTAL WORK Crystalline silicon substrate has been employed in this work in order to prepare porous layer in the front surface of the Si wafer. The PSi layer has been prepared by photochemical etching. Commercially n -type Si wafer of 0.05 Ω.cm resistivity was used as a starting material.The photochemical etching shown in figure (1) process used to prepare the PSi sample is shown in figure (1). After cleaning the sample it was immersed in 10% HF acid of 50% concentration in a Teflon beaker. The sample was mounted in the beaker on two Teflon tablets in such a way that the current required for the etching process could complete the circuit between the irradiated surface and the bottom surface of the silicon sample. Tungsten halogen lamp of 250 Watt was used as the photon beam source. A focus lens of focal length 5 cm was used to focus the photon beam. The irradiation time was 12 minutes. Far Infrared Photoconductive Detector Based on Multi-Wall Carbon Nanotubes Wasan R. Saleh 1 , Samar Y. Al-Dabagh 2 , Marwa A. Al-Azzawi 2 ,Ghaida S. Muhammed 1 , 3 Abdulla M. Suhail 1 Department of physics, College of Science, University of Baghdad,Baghdad ,Iraq 2 Department of physics, College of Science for Women, University of Baghdad, Baghdad ,Iraq 3 Department of Optics Techniques, Dijlah University College, Baghdad ,Iraq