Effect of growth interruption on the electrical and optical characteristics of InP/InGaAs HEMT structures

The effect of growth interruption on the top interface of the InGaAs layer in InP/In0.53Ga0.47As/InP heterostructures grown by molecular beam epitaxy was studied by Hall measurements, photoluminescence (PL) spectroscopy and h igh-resolution X-ray diffraction (HR-XRD). PL results from multiple quantum well structures (three: stacked InGaAs quantum wells of 10, 20 and 40 Angs trom width lattice matched to 300 Angstrom InP barriers) indicated an optim um interruption time of similar to 70 s for obtaining the minimum PL line w idth. Lattice matched high-electron mobility transistor structures were gro wn using different growth interruption times similar to MQW structures. A m aximum electron mobility of 3500 cm(2)/Vs and 15 900 cm(2)/V s at 300 K and 77 K, respectively, was measured. This time approximately corresponds to t he minimum PL line width obtained for the quantum well structure. The varia tion of the electron mobility with the growth interruption time was attribu ted to the formation of a thin InAsP or InGaAsP layer on the surface of the InGaAs at the InGaAs/InP heterointerface similar to MOVPE-grown samples. P L and HR-XRD results indicate that a similar phenomenon may be operative in MBE-grown layers also, and an optimum interruption time may provide abrupt interfaces with better electrical and optical properties. (C) 2000 Elsevie r Science B.V. All rights reserved.