Investigation of the quantum confinement effects in Ge dots by electrical measurements

The quantum confinement effects of Ge quantum-dots (QDs) grown by molecular beam epitaxy (MBE) are investigated by capacitance–voltage (C–V), admittance spectroscopy, and deep level transient spectroscopy (DLTS). The potential height of hole in the Ge dot obtained by C–V intercept, admittance spectroscopy and DLTS are 0.335, 0.341, and 0.338 eV, respectively. The DLTS method is also used to observe the changes of hole concentration, activation energy (Ea), and capture cross-section with filling time duration (tp) and bias voltage. The results show that the hole concentration in the Ge quantum-dots is a function of the pulse duration (tp) and reversed bias voltage, the activation energy and capture cross-section decrease with the increasing filling time duration due to the Coulomb charging effect. # 2003 Elsevier B.V. All rights reserved