Electrical characteristics of a metal–insulator–semiconductor memory structure containing Ge nanocrystals

A metal–insulator–semiconductor structure device with Ge nanocrystals in SiO₂ was synthesized and the electrical characteristics were investigated. Capacitance–voltage (C–V) curves show hysteresis and the measurements indicate that the device has charge storage effects and stores more holes than electrons. For decreasing measurement frequencies from 1 MHz to 500 Hz, both branches of the C–V hysteresis shift in the positive voltage direction. The slope of the left flank of the C–V hysteresis curve becomes stretched out with decreasing frequency. The slope of the right one appears frequency independent, while there is a small hump/step on the right flank of the C–V hysteresis curve for the lower frequency cases (500 Hz and 1 kHz). The role of Si/SiO₂ interface states is discussed.