Spin-dependent photoconductivity spectrum of dislocated silicon

Abstract

In the previous paper (1) the first observation of spin-dependent recombination at dislocations in Si was reported. The resonant decrease of photoconductivity was observed under conditions of an EPR experiment using microwave power modulation and signal detection by a lock-in amplifier. This method reveals only the integral from of the resonant signal. Moreover, the signal under investigation appears on the background of a synchronous but non-resonant signal of magnetoresistive origin(2). The last signal increases with lowering the temperature approximately a s the square of the current carrier mobility, making the measurements of spin-dependent photoconductivity at the lowest temperatures impossible.

Giant spin-dependent photo-conductivity in GaAsN dilute nitride semiconductor

“…The dependence of the recombination time on the relative spin orientation of photogenerated carriers on paramagnetic centers, namely the spin dependent recombination (SDR) has been known for over 50 years since the first optically detected magnetic resonance (ODMR) experiments carried out by Geschwind et al 1 in Al 2 O 3 . It has been observed in surface centers on crystalline silicon 2,3 and on several systems including dislocated silicon 4 , amorphous silicon 5 and later on in (Al)GaAs [6][7][8] . In dilute nitride GaAsN samples SDR has been evidenced with record high values at room temperature in photoluminescence (PL) experiments [9][10][11][12][13] and recently in photoconductivity (PC) measurements 14 , stimulating new applications of the SDR as a light-or electron spinpolarization detector.…”

Observation of a Novel Electron Paramagnetic Resonance in Germanium Containing Dislocations

“…In fact, we believe that the negative absorption is actually due to a decrease in sample conductivity detected by the cavity electric field rather than to the usual EPR magnetic dipole absorption. 7 The apparatus used was a He-cooled microwave (22-26 GHz) superheterodyne spectrometer with an optical port and a He-cooled shutter. Magnetic field modulation and lock-in detection were used to record the derivative of the absorption signal.…”

Detección del flip-flop de los centros paramagnéticos del GaAsN mediante bombeo óptico en régimen pulsado

“…La primera parte del proceso de recombinación se lleva acabo en un tiempo mucho menor ( entre 1 ps y 150 ps ) que la segunda (1 ns); los centros son saturados rápidamente después se vacían y se polarizan en la misma dirección que los electrones de la BC Figura 2.1 (d), esto impide la recombinación de electrones de la banda de conducción polarizados en una dirección y favorece la recombinación de los electrones polarizados en la BC en la dirección contraria [51]. Este mecanismo ha sido observado en diferentes sistemas como Silicio dislocado [62,63], Silicio amorfo [63,64] y en centros paramagnéticos profundos en GaAs. [4,65].…”