The size dependence of the optical and electrical properties of Ge quantum dots deposited by pulsed laser deposition

The optical and electrical properties of Ge quantum dots (QDs) deposited by pulsed laser deposition in a Si(1 0 0) matrix have been studied. Narrowband photoluminescence emission shifted from 0.8 to 0.74 eV with the size of the Ge dots increasing from 5 to 20 nm. At the same time, the photocurrent peaks shift from a 1.55 to 1.75 mu m long wavelength. The resistance and capacitance of Ge QDs are measured as a function of temperature. The largest absolute value of the temperature coefficient of resistance and capacitance exceeds 4 k Omega K-1 and 144 pF K-1 in the temperature range of 220-270 K, respectively. The properties of the Ge dots expected from quantum confinement effects have potential applications in light emitting devices and infrared detectors.