Fast C-V method to mitigate effects of deep levels in CIGS doping profiles

In this work, methods to determine more accurate doping profiles in semiconductors is explored where trap-induced artifacts such as hysteresis and doping artifacts are observed. Specifically in CIGS, it is shown that this fast capacitance-voltage (C-V) approach presented here allows for accurate doping profile measurement even at room temperature, which is typically not possible due to the large ratio of trap concentration to doping. Using deep level transient spectroscopy (DLTS) measurement, the deep trap responsible for the abnormal C-V measurement above 200 K is identified. Importantly, this fast C-V can be used for fast evaluation on the production line to monitor the true doping concentration, and even estimate the trap concentration. Additionally, the influence of high conductance on the apparent doping profile at different temperature is investigated

Deep levels in a-plane, high Mg-content MgxZn1-xO epitaxial layers grown by molecular beam epitaxy

Deep level defects in n-type unintentionally doped a-plane MgxZn1−xO, grown by molecular beam epitaxy on r-plane sapphire were fully characterized using deep level optical spectroscopy (DLOS) and related methods. Four compositions of MgxZn1−xO were examined with x = 0.31, 0.44, 0.52, and 0.56 together with a control ZnO sample. DLOS measurements revealed the presence of five deep levels in each Mg-containing sample, having energy levels of Ec − 1.4 eV, 2.1 eV, 2.6 V, and Ev + 0.3 eV and 0.6 eV. For all Mg compositions, the activation energies of the first three states were constant with respect to the conduction band edge, whereas the latter two revealed constant activation energies with respect to the valence band edge. In contrast to the ternary materials, only three levels, at Ec − 2.1 eV, Ev + 0.3 eV, and 0.6 eV, were observed for the ZnO control sample in this systematically grown series of samples. Substantially higher concentrations of the deep levels at Ev + 0.3 eV and Ec − 2.1 eV were observed in ZnO compared to the Mg alloyed samples. Moreover, there is a general invariance of trap concentration of the Ev + 0.3 eV and 0.6 eV levels on Mg content, while at least and order of magnitude dependency of the Ec − 1.4 eV and Ec − 2.6 eV levels in Mg alloyed samples

Unusual Formation of Point-Defect Complexes in the Ultrawide-Band-Gap Semiconductor β-Ga2 O3

Understanding the unique properties of ultra-wide band gap semiconductors requires detailed information about the exact nature of point defects and their role in determining the properties. Here, we report the first direct microscopic observation of an unusual formation of point defect complexes within the atomic-scale structure of β-Ga2O3 using high resolution scanning transmission electron microscopy (STEM). Each complex involves one cation interstitial atom paired with two cation vacancies. These divacancy-interstitial complexes correlate directly with structures obtained by density functional theory, which predicts them to be compensating acceptors in β-Ga2O3. This prediction is confirmed by a comparison between STEM data and deep level optical spectroscopy results, which reveals that these complexes correspond to a deep trap within the band gap, and that the development of the complexes is facilitated by Sn doping through increased vacancy concentration. These findings provide new insight on this emerging material's unique response to the incorporation of impurities that can critically influence their properties

Modulation-doped beta-(Al0.2Ga0.8)2O3/Ga2O3 Field-Effect Transistor

Modulation-doped heterostructures are a key enabler for realizing high mobility and better scaling properties for high performance transistors. We report the realization of modulation-doped two-dimensional electron gas (2DEG) at beta(Al0.2Ga0.8)2O3/ Ga2O3 heterojunction using silicon delta doping. The formation of a 2DEG was confirmed using capacitance voltage measurements. A modulation-doped 2DEG channel was used to realize a modulation-doped field-effect transistor. The demonstration of modulation doping in the beta-(Al0.2Ga0.8)2O3/ Ga2O3 material system could enable heterojunction devices for high performance electronics

248-Empathy and Pro-environmental Behaviors: Investigating Human Altruism and its Link to Pro-environmental Behaviors

Through the empathy-altruism hypothesis, Batson predicts empathetic concern influences altruistic motivation, which may lead to helping behaviors (Batson et al., 2014). Environmental researchers borrowed this idea and have produced a rich literature showing that empathy is associated with pro-environmental behaviors (PEB). This poster describes an ongoing literature review of this area of research. Our preliminary results show that empathy and associated constructs consistently predict PEB, although these relations are often of modest size. However, the literature is somewhat theoretically confused with no overarching explanation of why these relations exist. We hope to remedy this in our review by examining whether the specific factors that Batson found essential in the human altruism literature also apply to the environmental literature. For instance, the human altruism literature shows that empathy predicts helping only when the potential target is perceived as needy and deserving. Our review will examine whether this and other features of Batson’s theory help sharpen the predictions in the environmental literature. To accomplish this, we are conducting a systematic search of both PsycInfo and Google Scholar using pre-specified search terms with strict criteria about eligible studies

Test of an Adolescent Anxiety Sensitivity Amelioration Program (AASAP) for At-Risk Youth

Adult research supports the effectiveness of targeting the malleable vulnerability factor of anxiety sensitivity (AS) in terms of preventing panic specifically and anxiety psychopathology generally. Risk factor research suggests AS modification among youth has implications for panic as well as generalized anxiety disorder (GAD). However, very little work has evaluated the impact of AS reduction among youth, which is unfortunate given adolescence is a period of “core risk” in terms of anxiety disorder onset. Further, no work has considered the effect of such a program on GAD-relevant outcomes, nor has any work included family-level intervention factors, despite evidence suggesting parents likely play a critical role in promoting prevention programming. To address these notable gaps in the literature, the primary aim of this project was to experimentally test the effects of an Adolescent Anxiety Sensitivity Amelioration Program (AASAP) among a sample of 69 adolescents (10 to 14 years) with elevated levels of AS. High AS youth and a parent were randomly assigned to either the AASAP, which consists of a single 50min session of psychoeducation as well as experimenter- and parent-led interoceptive exposures, or a general health information control condition. As expected, adolescents in the intervention condition evidenced decreased levels of AS and generalized anxiety symptoms compared to adolescents in the control condition at follow-up. Contrary to hypotheses, however, no differences were detected in panic- and GAD-relevant vulnerability indexed using sophisticated challenge procedures. Findings are discussed in terms of the development of the specified psychoSocial intervention program for adolescents targeting empirically supported processes and its short-term effects on anxiety-relevant outcomes

The Effects of Maternal Information Transmission on Daughters\u27 Responding to a Voluntary Hyperventilation Challenge

Contemporary models of panic etiology would benefit from additional tests of how fear of internal cues is acquired. Drawing from literature suggesting parent-to-child verbal information transmission is one pathway by which fear of external stimuli is learned, the current study is designed to address the effects of this pathway on fearful responding to internal cues (i.e., somatic perturbation produced by a voluntary hyperventilation challenge). Specifically, 53 mothers of adolescent females between the ages of 10 and 14 years were randomly assigned to either share negative or positive information regarding their experience with a voluntary hyperventilation challenge prior to their daughters undergoing an identical challenge procedure. It was hypothesized that daughters in the negative information condition would evidence greater fear-relevant responding to the challenge than those in the positive information condition. Unexpectedly, no significant differences between groups emerged regarding daughters\u27 response to the hyperventilation challenge. Results are discussed in terms of their implications for developmentally sensitive perspectives on panic vulnerability

A Process Development Study on Reducing the Anisotropy while Maintaining the Strength of Extruded Aluminum Alloy 2195 through Heat Treatment

The purpose of this study was two-fold: develop an aging curve for extruded 2195 aluminum and test the magnitude of the anisotropy in the extrusion throughout the aging process. Two aging curves were developed, one at 290oF and the other at 320oF, through hardness tests of aged samples. The hardness was found to change, from approximately 72 HRB to 90 HRB, within the first 6 hours and not change more than 2 HRB in the 42 hours following. It was determined that the 320oF temperature was more promising due to faster aging time, and the anisotropy study proceeded with that temperature. Samples were aged at 320oF for 6, 18, 28, and 48 hours and tensile tested. These aging times were chosen due to interesting characteristics found during aging. The researchers measured yield strength to determine the magnitude of the anisotropy throughout the aging time