Incorporation of the noncentrosymmetric crystalline structure of III-V semiconductors into the design of novel optoelectronic devices

The use of heterostructures in the design of semiconductor devices has resulted in not only the realization of enhanced performance as compared to homostructure-based devices, but has opened up possibilities for novel optoelectronic and electronic applications that are otherwise not possible with homostructures. In addition to the advantages provided by "band-engineering" in III-V systems such as In/Al/GaAs/P and In/Al/GaN, polar semiconductors can be utilized in order to further widen the realm of electronic and optoelectronic applications by making use of the high second-order susceptibility and high piezoelectric coefficients due to the non-centrosymmetric crystalline structure.;In particular, the potential for realization of a compact, short-wavelength, GaAs-based laser emitting at close to 500nm has been investigated theoretically and experimentally. Such a device, which makes use of the high optical nonlinearity of GaAs as well as the piezoelectric effect, may find application in enhanced-density optical storage, full-color displays, and spectroscopy. In addition, the potential for realization of high-speed, high-power electronic circuitry utilizing the piezoelectric effect in order to obtain a high-mobility, high-density 2-DEG in the strained In/Al/GaN material system is also discussed. Considerations for the design of potential HEMT structures as well as recently obtained characteristics for an MBE-grown AlGaN/GaN high electron mobility transistor (HEMT) on (0001)-oriented sapphire are presented.;Aside from the benefits of the piezoelectric effect and optical-nonlinearity which may be achieved by employing the non-centrosymmetric crystalline structure of III-V semiconductors, growth of such polar materials as the III-V's on nonpolar substrates presents difficulties which must be circumvented. Such is the case for growth of GaAs on Si, for which the formation of anti-phase domains, lack of electrical neutrality at the epilayer/substrate interface, and the high-dislocation densities render the one-step growth of GaAs-based opto-electronic device structures on Si-based electronic structures previously unsuitable for commercial application. One way of potentially circumventing the difficulties of polar-on-nonpolar growth is demonstrated by way of the realization of an AlGaAs/GaAs heterostructure bipolar transistor on Si (311).