Search

We proposed a type of heterostructure by combining two photonic crystals (PCs) consisting of alternating negative-index materials and positive-index materials layers. It is demonstrated by transfer matrix method that the proposed structure has a polarization-independent omnidirectional band gap (OBG), which is independent of the incident angle for both TE and TM polarizations. Compared to a single PC, the frequency range of the OBG in a heterostructure can be notably enlarged. Such a structure has potential applications in improving planar microcavities, optical fibers, and Fabry-Pérot resonators, etc. [ABSTRACT FROM AUTHOR]

Al[sub 0.35-δ]In[sub δ]Ga[sub 0.65]N/GaN heterostructures have been studied by using transmission electron microscopy, photoluminescence, and Shubnikov–de Haas (SdH) measurements. In the sample of δ<0.01%, two SdH oscillations beat each other due to the population of the lowest two subbands. The carrier concentrations of these two subbands are 1.398 and 1.248×10[sup 13] cm[sup -2] and the electric field at the interface is reduced to 2.19×10[sup 4] V/cm, which is one order of magnitude smaller than that of Al[sub 0.35]Ga[sub 0.65]N/GaN heterostructure. We suggest that a small fraction of In atoms in the Al[sub 0.35-δ]In[sub δ]Ga[sub 0.65]N can be used as a tuning parameter to control the strain and the piezoelectric field at the interface. © 2002 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Investigates the measurement of the conduction-band discontinuity in pseudomorphic In[sub x]Ga[1-x]As/In[sub 0.52]Al[sub 0.48]As heterostructures. Use of strained quantum wells; Effects of the conduction-band nonparabolicity on the Fermi potential; Ways to obtain the conduction-band discontinuity at the spacer-barrier interface.