Long-wavelength photodiodes based on Ga1-xInxAsySb1-y with composition near the miscibility boundary

The possibility of using liquid-phase epitaxy to obtain Ga1-xInxAsySb1-y so lid solutions isoperiodic with GaSb near the miscibility boundary is invest igated. The effect of crystallographic orientation of the substrate on the composition of the solid solutions grown in this way is examined, and the i ndium concentration is observed to grow from 0.215 to 0.238 in the Ga1-xInx AsySb1-y solid phase in the series of substrate orientations (100), (111)A, (111)B. A change in the composition of the solid solution leads to a shift of the long-wavelength edge of the spectral distribution of the photosensi tivity. The use of a GaSb (111)B substrate made it possible, without loweri ng the epitaxy temperature, to increase the indium content in the solid pha se to 23.8% and to create long-wavelength photodiodes with spectral photose nsitivity threshold lambda(th) 2.55 mu m. The primary characteristics of su ch photodiodes are described, along with aspects of their fabrication. The proposed fabrication technique shows potential for building optoelectronic devices (lasers, LED's, photodiodes) based on Ga1-xInxAsySb1-y solid soluti ons with red boundary as high as 2.7 mu m. (C) 1999 American Institute of P hysics. [S1063-7826(99)01802-5].