Surface Science 168 (1986) 423-438 North-Holland, Amsterdam RHEED STUDIES OF HETEROJUNCTION AND QUANTUM WELL FORMATION DURING MBE GROWTH - FROM MULTIPLE SCATTERING TO BAND OFFSETS B A JOYCE, P J DOBSON, J H NEAVE and K WOODBRIDGE Phthps Research Laboratortes, Redhtll, Surrey RH1 5HA, UK Jlng ZHANG Phvsw+ Department. Imperial College of Sctence and Technology. Prince Consort Road, South Ken~mgton, London SW7 2AZ, UK and P K LARSEN and B BOLGER Phthps Research Laboratortes, Phthps Nederlandse Bedrqven BV. Emdhoven. The Netherlands Received 10 June 1985, accepted for pubhcatlon 14 June 1985 The basic concepts and first-order growth model derived from the RHEED intensity OScllla- t~on techmque are described and the hm~tatlons imposed by the experimentally demonstrated multiple-scattering nature of the diffraction process are indicated Despite these restrictions the value ol the techmque is illustrated m relation to growth mechamsm studies, heterojunct~on and quantum well interface formation and as a process control momtor 1. Introduction The combmatlon of molecular beam epltaxy (MBE) with reflection high- energy electron diffraction (RHEED) has proved to be extremely powerful, largely because the forward scattermg geometry of RHEED permits measure- ments to be made during growth The conventional apphcatlon of RHEED is to monitor surface reconstruction, morphology and disorder [1], but it has recently been shown [2-5] that it can also be used to study MBE growth dynamics and semiconductor heterolunctton formation This has now been extended to include beam flux callbrat~on, growth rate control and quantum well thickness determination [6,7] The surface symmetry of a wide range of stolchtometry-dependent recon- structions of GaAs(001) surfaces has been estabhshed [8,9], of which the best 0039-6028/86/$03 50 © Elsevier Science Pubhshers B V (North-Holland Physics Pubhshmg Division)