J. Opt. Commun., Vol. 32 (2011), pp. 101–106 Copyright © 2011 De Gruyter. DOI 10.1515/JOC.2011.026 Detectivity Performance of Quantum Wire Infrared Photodetectors Ashraf Nasr 1; 1 Radiation Engineering Dept., NCRRT, Atomic Energy Authority, Egypt Abstract. The manuscript is devoted to calculate the de- tectivity, Figure of merit, of the quantum wire infrared photodetectors (QRIPs). The importance arises from two points. Firstly, the QRIPs give a stable and controllable performance in comparison with quantum dot infrared pho- todetectors (QDIPs). Secondly, the gap; difference between the photo and dark currents, is high enough to obtain a distinguished responsivity and detectivity. So, the depen- dence of detectivity behavior on the QRIPs parameters is discussed. From the results, one can notice that the supe- riority of QRIPs over the QDIPs which gives higher values of detectivity, about ten times or higher the latter under the same conditions. Hence, an improvement of the responsiv- ity and detectivity of QRIPs compared to QDIPs has been perceived. Keywords. Nanotechnology IR detectors, quantum wires, infrared photodetectors, photo and dark current, responsiv- ity and detectivity, average quantum wire density, lateral size, operating temperatures. PACS ® (2010). 78.67.Lt, 73.63.Nm, 73.21.Hb. 1 Introduction High.5 bit rate (more than Gbit=s) optical, and space com- munications systems, thermal detection, night vision, and chemical analysis toward the researcher to nanotechnol- ogy devices. One of them is the quantum infrared pho- todetectors (QIRPs) that are based on intersubband tran- sitions idea. Modern research groups in the field of nanotechnology detectors have a most interest to these semiconductor-based detector devices. Because of the sim- plicity of fabrications processes, lower cost, broaden spec- trum response, and matching compounds and size for re- cent nano-optoelectronic components in comparison to the Corresponding author: Ashraf Nasr, Radiation Eng. Dep. NCRRT, 3 Ahmed El-Zomor, 8th. District, Nasr city, P.O. Box. 29, Egypt, currently in sabbatical leave at College of Computer, Qassim University, P.O.B. 6688, Buryadah 51453, KSA; E-mail: Ashraf.nasr@gmail.com. Received: November 29, 2010. Accepted: March 17, 2011. commercial IR detectors such as HgCdTe [1–7]. QIRPs are classified to three categories according to quantization di- mensions or degree of confinements. So, in the case of one dimension quantization or confinement (1D) the quan- tum well infrared photodetectors (QWIPs) are obtained. In the two, and three dimensional quantization (2D, and 3D), quantum wire and quantum dot infrared photodetec- tors (QRIPs, QDIPs) are composed respectively. QWIPs enjoyed some advantages such as high responsivity and de- tectivity in comparison to other types [8–10]. And also, it had been fabricated and commercial components are now available. But it is suffer from two main drawbacks that are coupling process and sensitivity to incident IR radia- tion. The QRIPs and QDIPs solved the mentioned prob- lems as a result of its geometry composition and sensitiv- ity to the normal incident IR. The main draw back of the latter devices, QRIPs and QDIPs, are the higher value of the obtained dark current in contrast to the QWIPs. And hence the smaller values of responsivity and detectivity are acquired, although a great effort is done to decrease the dark current as in [11, 12] or to develop a hybrid of QDs in wells (DWEEL) as in [13]. When QDIPs and QRIPs are com- pared with each other, as in previous work [6, 14, 15], the QRIPs denote a smaller values of dark current and large space region between it and induced photocurrent. So, more responsivity and detectivity can be obtained. Moreover, the QRIPs cover perspective multi color response for (Mid, and Far) (10 μm >  > 40 μm) IR region depending on the selectable compound parameters of QRIPs [6]. In this manuscript, the detectivity of QRIPs depending on its pa- rameters, lateral size a QR , average quantum wire density; † QR , doping density or electron sheet density; † D , num- ber of layers M , operating temperature; T , and transverse width size and period l QR ; L QR respectively are theoreti- cally discussed. In the theoretical investigation, the main problem in this case is that the determinations of the detec- tivity D  is relying on calculation of both dark and photo current in one equation, as we will define in the following sections. So, large memory and long time are required. It is obvious now to investigate this Figure of merit and also declare QRIPs position related to previous quantum detec- tors (QWIPs and QDIPs). In the reminder of the article, the basic assumption and model description is denoted in Section 2. The numerical results and discussion are given in Section 3. Hence, we terminate our research point by considering the important summary in the conclusion sec- tion. Brought to you by | Purdue University Libraries Authenticated Download Date | 6/7/15 11:53 AM