MOVPE overgrowth of metallic features for realisation of 3D metal-semiconductor quantum devices

We have studied the growth conditions for epitaxial overgrowth over metalli c features using low-pressure metalorganic vapour phase epitaxy. The aim of this study is to optimise the growth conditions and to establish a process ing sequence for the realisation of 3D metal-semiconductor quantum devices. First. we investigate the effect of the metal pattern (orientation and sha pe) on the resulting growth behaviour under fixed epitaxial conditions. The n we use the same pattern and vary the growth temperature in order to optim ise the lateral growth above the metal. An excellent crystalline quality of the overgrown material is thereafter demonstrated using transmission elect ron microscopy. Finally, it is demonstrated how these structures may be use d in two types of quantum devices, namely as storage elements in a semi-ins ulating layer and as an active part in a resonant tunnelling transistor. (C ) 2000 Elsevier Science B.V. All rights reserved.