G. Zapalac

Simulation of a Novel Cooling System for a Closed Greenhouse

G. Zapalac

A simulation of a cooling system for a closed greenhouse is described. The cooling system relies upon cool ambient temperatures during the night and morning to discharge heat accumulated within the greenhouse during the day. Radiative heat into the greenhouse is transferred …

Simulation of a convectively-cooled unventilated greenhouse

G. Zapalac

A simulation is presented to evaluate a novel cooling system for an unventilated greenhouse. The greenhouse is cooled during the day by transferring heat in the greenhouse air into a reservoir of water using an unpressurized droplet system. During the night and …

Voltage-Induced Charge Redistribution in Cu(In,Ga)Se2 Devices Studied With High-Speed Capacitance–Voltage Profiling

Jeff Bailey, Dmitry Poplavskyy, G. Zapalac, Lorelle M. Mansfield et autres

Devices made from Cu(In,Ga)Se2(CIGS) solar cell material have been evaluated with high-speed capacitance-voltage profiling after stepwise voltage changes. The changes primarily affect near-interface charge at deep acceptors within the CIGS absorber layer and generate temperature-dependent capacitance changes observed in deep-level transient spectroscopy …

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The role of oxygen doping on elemental intermixing at the PVD‐CdS/Cu (InGa)Se2 heterojunction

Xiaoqing He, Peter Ercius, Joel B. Varley, Jeff Bailey et autres

Abstract Elemental intermixing at the CdS/CuIn1−xGaxSe2 (CIGS) heterojunction in thin‐film photovoltaic devices plays a crucial role in carrier separation and thus device efficiency. Using scanning transmission electron microcopy in combination with energy dispersive X‐ray mapping, we find that by controlling the oxygen …

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Optical Spectroscopic Probes of Degradation and Metastability in Polycrystalline (Ag,Cu)(In,Ga)Se2 Absorbers

Andrew J. Ferguson, P. Dippo, Darius Kuciauskas, Rouin Farshchi et autres

We employ optical spectroscopic probes, based on steady-state photoluminescence (SSPL) and time-resolved photoluminescence (TRPL) excitation spectroscopy to spatially and energetically resolve metastable defects in polycrystalline (Ag,Cu)(In,Ga)Se2(ACIGS) absorbers. First, we show that ACIGS has similar potential fluctuations as CIGS; that is alloying with …

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Investigation of Dark Heat and Light Soaking Treatment on Cu(In,Ga)Se2 Solar Cells using Impedance Spectroscopy

G. Zapalac, Rouin Farshchi, Jeff Bailey, Dmitry Poplavskyy

Cu (In,Ga)Se2solar cell material was measured by impedance spectroscopy before and after 1000 hours of 85 °C dark heat treatment to investigate the impact of reducing the back electrode pre-selenization. Each condition was measured before and after 16 hours of light soaking …

Inclusive D*(plus/minus) production in photon-photon collisions

M. Alston‐Garnjost, R. E. Avery, A. Barker, D. Bauer et autres

The TPC/Two--Gamma Collaboration has measured the inclusive cross section for production of charmed n-± mesons in photon-photon collisions.The reaction utilized was e+e---> e+e-n-±x, with n-±--> D 0 1f'±, D 0 --> /(~1f'±, and either zero or one outgoing e± detected.The result, ir(e+e---> …

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

Pran K. Paul, Jeff Bailey, G. Zapalac, Aaron R. Arehart

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 …

Optimizing CdS Buffer Layer For CIGS Based Thin Film Solar Cell

Weijie Zhang, Korhan Demirkan, G. Zapalac, David Spaulding et autres

CdS buffer layer is one of the important factors that affect the conversion efficiency in CIGS-based solar cell. In our PVD CdS process optimization, different sputter powers in the early stage of CdS film growth were tested. Higher sputter power in the …

Simulation of drive-level capacitance profiling to interpret measurements on Cu(In, Ga)Se2Schottky devices

G. Zapalac, Jeff Bailey

A simulation is presented for drive-level capacitance profiling (DLCP) of Schottky diodes that allows a continuous distribution of defect states in both energy and depth. The simulation is used to interpret high frequency DLCP data for a Cu(In,Ga)Se2Schottky device.

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

Pran K. Paul, Jeff Bailey, G. Zapalac, Aaron R. Arehart

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 …

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Cd doping at PVD-CdS/CuInGaSe2 heterojunctions

Xiaoqing He, Tadas Paulauskas, Peter Ercius, Joel B. Varley et autres

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