Volume 3, Issue 1, Autumn 2010, Page 3-26

Linear Adaptive Antenna Array Geometry Effects on Radiation Pattern

A.H. Sallomi; H.M. Mikhlif; S.R. Salim

Iraqi Journal of Applied Physics Letters, Volume 3, Issue 1, Pages 3-6

Over the last few years, the number of subscribers to wireless services has increased at an explosive rate. Smart-antenna technology compared to conventional antenna has the ability to increase the number of simultaneous users, and satisfy the requirements of spectral efficiency, and coverage in wireless communication systems. In this paper the radiation pattern and performance of linear smart antenna array is investigated by considering multiple directions of arrivals of signals. The simulations done confirmed that smart antenna systems using Least Mean Square (LMS) algorithm are able to adjust their pattern to enhance desired signals, and reduce interference. The results also show that smart antenna radiation patterns are related to the number of elements in the array, the inter-element spacing, and amplitude distribution.

Synchronization Scheme for Secured Communications System Based on Chaotic Signals

P.E. Steran

Iraqi Journal of Applied Physics Letters, Volume 3, Issue 1, Pages 7-10

In this work, a numerical investigation of a synchronization scheme for secure communication implemented with nonlinear optical ring cavities is performed. We have demonstrated that masking the information in a chaotic optical wave from a nonlinear ring cavity is technically feasible in a secured communication system. The synchronization is robust and analog information transmission is suitable for the specific case considered.

Quantum Limit Characterization of Signal-to-Noise Ratio using Phase- Shift Keying in Homodyne Detection

N.J. Shukur

Iraqi Journal of Applied Physics Letters, Volume 3, Issue 1, Pages 11-14

In this work, a mathematical treatment for the quantum limit of signal-to-noise ratio (SNR) in homodyne coherent detection was presented. This treatment is based on the case of balanced detection when the incident signal power is much lesser than the local oscillator power when the efficient AC coupling is assumed. The final results were obtained from an analytical expression of SNR dependent of the average number of incident photons and the quantum efficiency.

Polynanocrystalline CuIn3Se5 Thin Film Photoabsorber Layer Produced by Pulsed-Laser Deposition

A. Twerianovich; S. Berzeneev; E. Barissov

Iraqi Journal of Applied Physics Letters, Volume 3, Issue 1, Pages 15-18

Polycrystalline bulk CuIn3Se5 samples for pulsed laser deposition (PLD) targets were synthesized in evacuated quartz ampoules by vacuum melting of 99.999% pure elements. All the polynanocrystalline CuIn3Se5 thin films were deposited onto the glass and glass/ITO substrates by using the PLD technique. The synthesized bulk samples and deposited films were tested by using the XRD analysis. The time–temperature regime of PLD process was developed for preparation of polynanocrystalline CuIn3Se5 thin films with the same composition as the source target. We have used advanced 3-stages temperature-time regime. The thickness of prepared CuIn3Se5 layers was in the range from 300nm till 450nm. The influence of the thermal annealing on the photovoltaic properties and morphology of the as-deposited CuIn3Se5 layers was investigated. The technique of preparation of high photosensitive polynanocrystalline thin CuIn3Se5 films of n-type conductivity was elaborated.

Characterization of E-Mode InZnO Thin Film Transistors Produced by DC Sputtering Technique

G.M.A. Yussif; A.M.H. Enagar; A.S. Megazi

Iraqi Journal of Applied Physics Letters, Volume 3, Issue 1, Pages 19-22

In this work, InZnO and InGaZnO were used as channel layers to fabricate enhancement mode thin film transistors on glass and flexible transparent substrate. The SiO2-In2O3-ZnO system and N2 plasma incorporated IZO film were grown to get a better controllability of the carrier concentration during the film growth. Hydrogen plasma and oxygen plasma effects on the TCO films and the TFTs were investigated.

Profiling of Antimony Diffusivity in Silicon Substrates using Laser- Induced Diffusion Technique

O.A. Hamadi

Iraqi Journal of Applied Physics Letters, Volume 3, Issue 1, Pages 23-26

In this work, profiles of laser-induced diffusion of antimony in silicon were presented. These profiles were considered to attempt enhancing of the silicon-based devices. This enhancement is attributed to the increasing achieved in the diffusion length within a certain layer of the active region in the device. Laser-induced diffusion is a perfect technique for improving the characteristics of electronic devices since it is flexible, contactless, clean and well controlled.