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 high-resolution X-ray diffraction (HR-XRD). PL results from multiple quantum well structures (three: stacked InGaAs quantum wells of 10, 20 and 40 Angstrom width lattice matched to 300 Angstrom InP barriers) indicated an optimum interruption time of similar to 70 s for obtaining the minimum PL line width. Lattice matched high-electron mobility transistor structures were grown using different growth interruption times similar to MQW structures. A maximum 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 the minimum PL line width obtained for the quantum well structure. The variation of the electron mobility with the growth interruption time was attributed 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. PL 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 Elsevier Science B.V. All rights reserved.