Different InAs quantum dot structures grown on InGaAlAs lattice matched to InP were investigated for quantum dot infrared photodetectors. Extremely narrow photocurrent peaks were observed, demonstrating great potential for fine wavelength selection. Structures which can detect radiation beyond 10μm were developed. Polarization dependence measurements showed that the structures have a zero-dimensional character and are suitable for detection of normal incident light. On the other hand, structures containing coupled quantum wells showed a hybrid two-dimensional/zero-dimensional behavior.

InAs quantum dot structures grown on InGaAlAs have been investigated for midinfrared photodetection. Intraband photocurrent and absorption measurements, together with a full three-dimensional theoretical modeling revealed that a bound-to-bound optical transition, where the final state is about 200meV deep below the conduction band continuum, is responsible for the photogenerated current. The reported results strongly suggest that an Auger process plays a fundamental role in generating the observed intraband photocurrent. Photoluminescence and interband photocurrent spectra of the same structures further support the reached conclusions.

We studied the influence of the final state in a bound-to-quasibound transition in the photocurrent sign on quantum dot structures for photodetection. We measured a photocurrent with positive and a negative sign for the same external field for different wavelengths. This process can be seen for very small external applied bias voltages and when no bias is applied. For high external fields the photo excited electrons flows in the direction of the field, as expected.

Quantum dot infrared photodetectors are expected to be a competitive technology at high operation temperatures in the long and very long wavelength infrared spectral range. Despite the fact that they already achieved notable success, the performance suffers from the thermionic emission of electrons from the quantum dots at elevated temperatures resulting in a decreasing responsivity. In order to provide an efficient carrier injection at high temperatures, quantum dot infrared photodetectors can be separated into two parts: an injection part and a detection part, so that each part can be separately optimized. In order to integrate such functionality into a device, a new class of quantum dot infrared photodetectors using quantum dot molecules will be introduced. In addition to a general discussion simulation results suggest a possibility to realize such a device.

This study is part of an interdisciplinary analysis of the economic evaluation of the water resources of the Rio Grande region of New Mexico. It was elemental in obtaining dynamic water availabilities in time and space. The relationship of dynamic ground‐water availability and aquifer behavior under projected stresses was modeled by a ground‐water system simulator based on a mass balance of the hydrologic basin. Conditions from extreme dry to extreme wet were modeled, combined with a range of different water demands. A vast amount of information was thus obtained in the form of aquifer responses for different conditions. An analogous relationship was constructed from these data by stepwise multiple regression analysis and was of the following form λd = f (dn, L) where λd = change in water‐table elevation for the time period considered, dn= water‐table elevation at the end of the previous time period, and L = a lump factor combining surface‐water inflow and outflow, precipitation, and beneficial and nonbeneficial water uses. Other results readily obtainable from the simulation runs are river accretion or depletion curves as a function of time. These curves show the diversion effects of groundwater pumping upon the river.