REMOTE N-TYPE MODULATION DOPING OF INAS QUANTUM-WELLS BY DEEP ACCEPTORS IN ALSB

Due to the fact that impurities normally change their doping characters when they undergo shallow to deep transitions or deep-to-false-valence transitions, a single defect, such as a cation on an Sb site, can explain all of the following facts for nonintentionally doped AlxGa1-xSb alloys and InAs/AlxGa1-xSb superlattices and quantum-well structures: (i) Bulk GaSb is p type; (ii) bulk AlSb is semi-insulating; (iii) InAs/AlSb superlattices with InAs quantum wells thicker than a critical thickness d(c)(x=1.0) are n type, where the InAs shallow-deep critical thickness function d(c)(x) is around congruent-to 100- congruent-to 150 angstrom for 0.5 < x less-than-or-equal-to 1.0 for InAs/AlxGa]-xSb superlattices; (iv) InAs/AlSb superlattices with InAs quantum wells thinner than d(c)(x=1.0) are semi-insulating. In addition, the theory predicts that Al0.5Ga0.5Sb and AlSb will be semi-insulating when nonintentionally doped, but can be converted to p type by the application of hydrostatic pressure P: P > 90 kbar and P > 150 kbar, respectively. These changes of doping character, which lie outside the conventional effective-mass theory, occur often in type-II band-alignment systems, such as InAs/AlxGa1-xSb.