| Measurement of electrostatic interaction between a conductive atomic force microscopy tip and a semiconductor sample can provide data which can be processed and interpreted to give information about location and energies of localized electronic states on and below the sample surface. Potentially large amount information that describes the distribution of localized states in the sample can not be inferred from a single measurement of the electrostatic interaction. However, multiple measurements of the interaction with varying tip-sample separation and bias can yield enough data, which can be processed to estimate information about the state. Theoretical description of such a technique is given along with experimental methods for its realization. Application of the method using a sample with Indium Arsenide self-assembled quantum dots as trap centers is demonstrated. A quantum dot (QD) refers to a nanometer scale semiconductor structure embedded in a host crystal, in which electrons and holes can occupy certain discrete energy levels. These levels serve as localized states in the presented experiments. The method can be applied directly to characterization of novel thin dielectric films. With further development, it can potentially be applied to high spatial resolution characterization of dopant distributions. |
