The electronic energy levels of InAs quantum dots (QDs) have been measured with respect to the GaAs conduction band edge by employing capacitance–voltage spectroscopy with a method which accurately measures the height of the Schottky barrier. To do so, two samples have been grown by molecular beam epitaxy and processed in parallel with Ohmic and Schottky contacts. One sample has no InAs (neither wetting layer nor QDs) which allows an accurate measurement of the Schottky barrier height when the flat band condition is achieved on the device. The measured Schottky barrier height is 760 meV. The second sample has embedded InAs QDs. The measured s-like states of these QDs are 230 meV below the GaAs conduction band.

This work was partially supported by projects: Nanomat of the EC Growth Program, contract no. G5RD-CT-2001- 00545; Spanish MCYT under NANOSELF project TIC2002- 04096-C03-03 and SANDIE Network of Excellence Contract No. NMP4-CT-2004-500101.

3 páginas, 3 figuras, 1 tabla.-- PACS: 73.21.La Quantum dots; 73.20.At Surface states, band structure, electron density of states; 73.40.Ns Metal-nonmetal contacts; 73.30.+y Surface double layers, Schottky barriers, and work functions.

Peer reviewed