The bard offset cccuring at abrupt heterc-interface in heterojunction devices has been studied for many years. It has been demonstrated that by present developing technology

the fabrication of true abrupt or grede heterojunction seems not difficult. Particalarly

in the GaAs/AlGaAs system

MBE and MOCVD are available to grow for this purpose. However

relatively little research has been carried on the optical properties of hetero-interface of such layers. The spikes and notches in the discontinuous energy bard at the hetro-interface has never been observed directly.The purpose of this paper is to report a new PL phenomenon in LPE GaAs/AlGaAs heterojunction devices with grade quantum confinement.Special light doped and urdoped GaAs/AIGeAs fairples with different thickness are grown in general LPE system. Care is taken during the growth to pull the LPE system slider from the boat factly

and the clearances are small(~25nm)in order to have the interface as abrupt as possible. Selective and controllable chemical etch are used to make a set of step-etch samples with different layer thickness apart from heterc-interface for PL experiement. Liquid He cryostat

Ar laser

the 1M spectrometer

cooled

(77K) photomultiplier tube

quantum photometer and recorder are equiped for the PL measurmenl (Fig.l). The intensity of laser power and the temperature of the samples can be changed in a large scale dependent on the experiement.