This paper presents a theoretical analysis for the dark current characteristics of different quantum infrared photodetectors. These quantum photodetectors are quantum dot infrared photodetectors (QDIP), quantum wire infrared photodetectors (QRIP), and quantum well infrared photodetectors (QWIP). Mathematical models describing these devices are introduced. The developed models accounts for the self-consistent potential distribution. These models are taking the effect of donor charges on the spatial distribution of the electric potential in the active region. The developed model is used to investigate the behavior of dark current with different values of performance parameters such as applied voltage, number of quantum wire (QR) layers, QD layers, lateral characteristic size, doping quantum wire density and temperature. It explains strong sensitivity of dark current to the density of QDs/QRs and the doping level of the active region. In order to confirm our models and their validity on the practical applications, a comparison between the results obtained by proposed models and that experimentally published are conducted and full agreement is observed. Several performance parameters are tuned to enhance the performance of these quantum photodetectors through the presented modeling. The resultant performance characteristics and comparison among them are presented in this work. From the obtained results we notice that the total dark current in the QRIPs can be significantly lower than that in the QWIPs. Moreover, main features of the QRIPs such as the large gap between the induced photocurrent and dark current open the way for overcoming the problems of quantum dot infrared photodetectors.

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This paper presents algorithms for overcoming a common problem of gamma ray spectroscopy, namely the peak pileup recovery problem. Three different approaches are studied and evaluated within a spectroscopy system. The algorithms are evaluated by the means of parameters error and fitting error calculations. The first approach is a direct search based on Nelder-Mead technique without any derivatives in order to find the local minimum points. A Gaussian shape in conjunction with the peak height and its position of each pulse are used to construct the pulse. So, the main pulse parameters such as peak amplitude, position and width can be determined. The second algorithm is based on the nonlinear least square method. This approach has accuracy of recovering the original pulses with mean square error of 4.7306x10-12. In this paper another technique is tried. This technique which is proposed as third algorithm is based on a maximum peak search method combined with the first derivative method to determine peak position of each pulse. Comparison among these approaches is conducted in terms of parameters errors. The pulse parameters have been calculated and compared with the actual one. The second approach shows the best accuracy, for determining peak height and position, but the width parameter scored the highest error.

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