We propose and demonstrate evanescently-decoupled, solid-angle-optimized distributed Bragg reflectors (DBRs) for AlGaInP light-emitting diodes (LEDs). The thickness of each DBR layer is tuned to the wavelength slightly longer than the emission peak of the active medium in order to maximize the radiated power integrated over the top surface. In addition, to increase the horizontal radiation thro...

We consider (AlAs)n/(GaAs)n superlattices with random thickness fluctuations ∆n around the nominal period n. Using three-dimensional pseudopotential plane-wave band theory, we show that (i) any amount ∆n/n of thickness fluctuations leads to band-edge wavefunction localization, (ii) for small ∆n/n the SL band gap is pinned at the gap level produced by a single layer with “wrong” thickness n+∆n, ...

The scaling limit for VLSI gate oxide (SiO 2 ) is 15}20 As that is determined by the large direct-tunneling leakage current. Further scaling to improve device performance can be obtained using a higher dielectric constant material. We have studied the Al 2 O 3 to use as an alternative gate dielectric. To ensure good quality, Al 2 O 3 is thermally oxidized from MBE-grown AlAs or Al on Si-substra...

5-Aminolevulinate synthase (ALAS) is the first enzyme of the heme biosynthetic pathway in non-plant eukaryotes and the alpha-subclass of purple bacteria. The pyridoxal 5'-phosphate cofactor at the active site undergoes changes in absorptive properties during substrate binding and catalysis that have allowed us to study the kinetics of these reactions spectroscopically. Rapid scanning stopped-fl...

Cross-sectional scanning tunneling microscopy has been used to investigate the effects of several key growth parameters on the resulting interfacial quality of AlAs/GaAs short period superlattices. For growth on top of AlGaAs layers, only superlattices grown with periodicity no smaller than 4 unit cells of GaAs and 2 unit cells of AlAs and grown with a minimum of 30 s of growth interrupt time a...

In this paper we report the results of a systematic investigation on the effects of electronic coupling on a series of G&-rmlt' l e quantum well samples in which the thickness of the G& layers was fixed a t s 2 5 L d the AlAs thickness varied between samples from 392 t o 62. Using the techniques of photoluminescence and p h o t o l ~ s c e n c e xcitation spectroscopy we have followed the posit...