Benefits of undergraduate participation in faculty research in natural resources

Graduate student assistance with faculty research is common in university natural resource programs. Traditionally, undergraduate students are involved less with research programs of faculty. The Uintah Basin Branch Campus of Utah State University provides a unique setting for developing research projects in natural resources that involve undergraduates. We use a research project on the control of greasewood (Sarcobatus vermiculatus) iin the Book Cliffs, Utah to illustrate the benefits and challenges for undergraduate students and faculty of collaboration on research. Students benefit by interacting with faculty outside the classroom; by applying classroom learning to field problems; and by working with natural resource management personnel. Faculty benefit by observing the ability of students to apply classroom learning to field situations; by maintaining a scholarly research program; and by interacting with students outside the classroom

Deliverable 9.1 - Report on mixtures and implementation strategy in Europe – Assessment of chemical mixtures under consideration of current and future regulatory requirements and scientific approaches

This report gives an overview on the regulatory processes and requirements for risk assessment of chemical mixtures, identifies gaps in the European legislation and summarises potential approaches for the health risk assessment of chemical mixtures

Self-aligning planarization and passivation for integration applications in III-V semiconductor devices

Cataloged from PDF version of article.This paper reports an easy planarization and passivation approach for the integration of III-V semiconductor devices. Vertically etched III-V semiconductor devices typically require sidewall passivation to suppress leakage currents and planarization of the passivation material for metal interconnection and device integration. It is, however, challenging to planarize all devices at once. This technique offers wafer-scale passivation and planarization that is automatically leveled to the device top in the 1-3-mum vicinity surrounding each device. In this method, a dielectric hard mask is used to define the device area. An undercut structure is intentionally created below the hard mask, which is retained during the subsequent polymer spinning and anisotropic polymer etch back., The spin-on polymer that fills in the undercut seals the sidewalls for all the devices across the wafer. After the polymer etch back, the dielectric mask is removed leaving the polymer surrounding each device level with its device top to atomic scale flatness. This integration method is robust and is insensitive to spin-on polymer thickness, polymer etch nonuniformity, and device height difference. It prevents the polymer under the hard mask from etch-induced damage and creates a polymer-free device surface for metallization upon removal of the dielectric mask. We applied this integration technique in fabricating an InP-based photonic switch that consists of a mesa photodiode and a quantum-well waveguide modulator using benzocyclobutene (BCB) polymer. We demonstrated functional integrated photonic switches with high process yield of >90%, high breakdown voltage of >25 V, and low ohmic contact resistance of similar to 10 Omega. To the best of our knowledge, such an integration of a surface-normal photodiode and a lumped electroabsorption modulator with the use of BCB is the first to be implemented on a single substrate

Investigation of reactive‐ion‐etch‐induced damage of InP/InGaAs multiple quantum wells by photoluminescence

The effects of CH4/H2 reactive ion etching (RIE) on the optical properties of an InP/InGaAs multiple‐quantum‐well structure have been investigated by low‐temperature photoluminescence (PL). The structure consisted of eight InGaAs quantum wells, lattice matched to InP, with nominal thicknesses of 0.5, 1, 2, 3, 5, 10, 20, and 70 monolayers, respectively, on top of a 200‐nm‐thick layer of InGaAs for calibration. The design of this structure allowed etch‐induced damage depth to be obtained from the PL spectra due to the different confinement energies of the quantum wells. The samples showed no significant decrease of luminescence intensity after RIE. However, the observed shift and broadening of the PL peaks from the quantum wells indicate that intermixing of well and barrier material increased with etch time. © 1995 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70403/2/JAPIAU-78-3-1528-1.pd