RESUMO
In this paper, effect of an introduced defect on electrical and optical properties of quantum box and spherical quantum dot is studied. 3D-self-consistent solution of the Schrödinger-Poisson equations for evaluation of the proposed complex quantum box and analytical solution for spherical quantum dot are used. It is shown that with increasing the defect size and height a considerable enhancement in matrix element, optical nonlinearities (second order, quadratic electro-optic effect and the resonant third order nonlinear susceptibilities), optical linear absorption coefficient ( 4.5 -10 nm, 10(-4) approximately 10(-2) m.V(-1), 10(-12) approximately 10(-9) m(2) / V (2) , 10(-11) approximately 10(-9) m(2) / V(2) and 4.7 x 10(2) approximately 3.8 x 10(4) cm(-1) respectively) and electroabsorption properties associated with intersublevel transition of centered defect quantum dot are examined. Also, it is shown that enhancement of optical nonlinearity is approximately independent of defect position that is so excellent from practical implementation point of view. A THZ-IR photodetector based on resonant tunneling spherical centered defect quantum dot (RT-SCDQD) operating at room temperature is also investigated. Inserting the centered defect in quantum dot increases the dipole transition matrix element and so increases the absorption coefficient considerably (1.05 x 10(6) approximately 7.33 x 10(6)at 83 microm ). Therefore the quantum efficiency in SCDQD structure enhances which leads to increasing the responsivity of the proposed system. The double barrier reduces the dark current. These improvements concludes to ultra high detectivity 5 x 10(16) 2.25 x 10(9) cm Hz (1/2)/W at 83 and 300 degrees K at 83 microm respectively.
