CODE - A NOVEL SINGLE STEP MOVPE TECHNIQUE FOR THE FABRICATION OF LOW-DIMENSIONAL DEVICES, QUANTUM WIRES AND QUANTUM DOTS

Compound and orientation dependent epitaxy (CODE) is a novel MOVPE phenomenon, applicable to the single step growth of low-dimensional devices and reduced dimensional structures such as quantum wires and quantum dots. This phenomenon arises in the growth of GaInAs/AIInAs/InP multi-layer structures on etched InP substrates, where selective deposition of the arsenic containing compounds can be achieved on specific crystal planes, together with non-specific growth of phosphorus containing compounds with an orientation dependent growth rate. For the arsenide compounds, optimum conditions have been defined to give zero sidewall growth and high quality, dislocation free, selective area growth. Under such conditions, GaInAs/InP/AIInAs quantum well and barrier structures remain clearly defined out to the etched rib edges. Reasons for loss of selectivity have also been determined. Explanations for the CODE phenomenon are discussed. The first observation of a two-dimensional electron gas (2DEG) on a {111} sidewall of a selectively grown GaInAs/InP heterostructure device structure is reported, together with details of the first resonant tunnelling structures grown by CODE.