Applied physics
N 2, 2003

Effect photoconductivity gain by Si p-n-junction containing quantum dots

A. V. Dvurechenskii, A. P. Kovchavsev, G. L. Kuryshev, I. A. Ryazantsev, A. I. Nikiforov, O. P. Pchelyakov
Institute of Semiconductor Physics, Siberian Branch RAS, Novosibirsk, Russia

   Si junction (of p-i-n-diode type) containing Ge of self-assembled quantum dots (SAQD). in a ~0.6 mm-thick near-surface layer were investigated. Analysis of photo- and electrophysical performances allowed to revel ~10—10³ Iph(V) photocurrent gain by p-n-junction at T = 78 K upon photodiode radiation with the photon energy corresponding to Si and Ge basic interband transitions. A model is proposed which assumes that SAQDs with a positive charge at T = 78 K turn out to by trapping centers for electrons/At "forward" voltages on a photodiode (V > 0.2), when the p-layer SAQDs are already partially outside the p-n-junction, there takes place electron capture on SAQDs as on adhesion centers under conditions of photocarrier optical generation in Si. In this case, excess concentration of the p-layer electrons forming oxsiton-type bound stares with quantum dots leads to lowering the p-n-junction potential barrier and photocurrent amplification.

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