GROWTH AND CHARACTERIZATION OF DIGITAL AND COMPOSITIONALLY GRADED ALGAAS GAAS NONRECTANGULAR QUANTUM-WELLS/

Narrow symmetric quantum wells with triangular and inverse parabolic s hapes have been grown by molecular beam epitaxy using digital and copo sitional grading techniques. Migration enhanced epitaxy was used in th e regions with the highest variation rate of the Al source temperature . This was measured in situ and the Al composition depth profile was m easured by secondary ion mass spectroscopy. A comparative study was ca rried out by photoluminescence, photocurrent and Hall measurements. It was found that the digital quantum wells had better optical and trans port properties than the compositionally graded ones.