The Hall factor in a quantum well structure with X or L-type indirect conduction valleys is calculated for various strain conditions. The two-dimentsional constant energy of occupied valleys are proven to be identical. As a result the Hall factor depends on the direction of occupied valleys to the growth direction, regardless of the number of occupied valleys. This work is widely applicable to the two-dimensional structure with indirect conduction minima for any growth direction and under different strain conditions.

Optical gain characteristics of 1.3 ㎛ type-II GaAsSb/InGaNAs/GaAs trilayer quantum well structures were studied using multi-band effective mass theory. The results were compared with those of 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structures. In the case of 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure, the energy difference between the first two subbands in the valence band is smaller than that of 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. Also, 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure shows larger optical gain than 1.3 ㎛ GaAsSb/InGaNAs/GaAs trilayer quantum well structure. This means that GaAsSb/InGaNAs/GaAs system is promising as long-wavelength optoelectronic devices for optical communication.