Influence of the annealing ambient on structural and optical properties of rare earth implanted GaN

GaN films were implanted with Er and Eu ions and rapid thermal annealing was performed at 1000, 1100 and 1200 ⁰C in vacuum, in flowing nitrogen gas or a mixture of NH₃ and N₂. Rutherford backscattering spectrometry in the channeling mode was used to study the evolution of damage introduction and recovery in the Ga sublattice and to monitor the rare earth profiles after annealing. The surface morphology of the samples was analyzed by scanning electron microscopy and the optical properties by room temperature cathodoluminescence (CL). Samples annealed in vacuum and N₂ already show the first signs of surface dissociation at 1000 ⁰C. At higher temperature, Ga droplets form, at the surface. However, samples annealed in NH₃+N₂ exhibit a very good recovery of the lattice along with a smooth surface. These samples also show the strongest CL intensity for the rare earth related emissions in the green (for Er) and red (for Eu). After annealing at 1200 ⁰C in NH₃+N₂ the Eu implanted sample reveals the channeling qualities of an unimplanted sample and a strong increase of CL intensity is observed

Optical doping of nitrides by ion implantation

A series of rare earth elements (RE) were implanted in GaN epilayers to study the lattice site location and optical activity. Rutherford backscattering spectrometry in the channeling mode(RBS/C) was used to follow the damage behavior in the Ga sublattice and the site location of the RE. For all the implanted elements (Ce, Pr, Dy, Er, and Lu) the results indicate the complete substitutionality on Ga sites after rapid thermal annealing at 1000°C for 2 min. The only exception occurs for Eu, which occupies a Ga displaced site. Annealing at 1200°C in nitrogen atmosphere at a pressure of IGPa is necessary to achieve the complete recovery of the damage in the samples. After annealing the recombination processes of the implanted samples were studied by above and below band gap excitation. For Er implanted samples besides the 1.54 μm emission green and red emissions are also observed. Red emissions from 5D0→7F2 and 3P0→3F2 transitions were found in Eu and Pr implanted samples even at room temperature

Perturbed angular correlations for Gd in gadolinium: in-beam comparisons of relative magnetizations

Perturbed angular correlations were measured for Gd ions implanted into gadolinium foils following Coulomb excitation with 40 MeV O-16 beams. A technique for measuring the relative magnetizations of ferromagnetic gadolinium hosts under in-beam conditions is described and discussed. The combined electric-quadrupole and magnetic-dipole interaction is evaluated. The effect of nuclei implanted onto damaged or non-substitutional sites is assessed, as is the effect of misalignment between the internal hyperfine field and the external polarizing field. Thermal effects due to beam heating are discussed.Comment: 37 pages, 15 figures, accepted for publication in NIM

Making it Work: Reframing College Student Off-Campus Employment as a High-Impact Practice

Working while attending college has become a reality of the student experience, especially for low-income, adult, and BIPOC students. Particularly, off-campus employment is commonplace but may not be fully understood by higher education professionals as an educationally effective activity. This paper is grounded in current literature on the necessity and the benefits of off-campus employment, along with the need for high-impact practices. We, the authors, encourage institutions to reframe off-campus employment as an activity that is educationally effective for those students who engage in it

Professor Oppressors: College Classrooms as Spaces of Racist and Sexist Microaggressions

This article describes minoritized college students’ encounters with faculty-generated or -condoned racial and gender microaggressions in college classrooms. The Racial Microaggressions Model (Pérez Huber & Solorzano, 2015) and the Taxonomy of Gender Microaggressions (Capodilupo et al., 2010) were used to inform the experiences of microaggressions of 88 college students with minoritized identities at seven institutions around the U.S. Based on the findings, the authors delivered recommendations for teaching and learning in four areas: faculty awareness and training; classroom management; policy, assessment, and evaluation of teaching; and improved mechanisms for student feedback

Exploring Messages African American Men Receive About Attending a Predominantly Whilte University

This article discusses the findings of a focus group study of 10 African American undergraduate men at a predominantly White Southern research institution. The authors explored African American men’s struggles with persistence through graduation. Findings suggest that prior to college, participants faced distracting messages about what it means to attend a PWI from their families, schools, and community. Implications for establishing partnerships with African American families, schools, and community organizations are discussed

Unfamiliar Territory: Faculty Discomfort about Interactions with Students During Out-of-Class Academic Initiatives

A considerable body of research exists on successful student outcomes from interactions with faculty. When such interactions do not take place research often cites issues of student discomfort with faculty members in out-of-class situations as reasons. This qualitative study with eight faculty members at a Southern research institution explored these issues from the faculty perspective. Findings show that faculty may have a similar sense of discomfort about interacting with students outside of the classroom. This has direct implications for the work of student affairs professionals attempting to recruit faculty for co-curricular academic initiatives. The authors offer recommendations for student affairs practice