@article{park_reitmeier_fothergill_zhang_muth_davis_2006, title={Growth and fabrication of AlGaN-based ultraviolet light emitting diodes on 6H-SiC(0001) substrates and the effect of carrier-blocking layers on their emission characteristics}, volume={127}, ISSN={["0921-5107"]}, DOI={10.1016/j.mseb.2005.10.019}, abstractNote={Abstract Growth, fabrication, and the electrical and optical characterization of ultraviolet light emitting diodes and their components, including AlxGa1−xN films, quantum wells (QWs), and ohmic contacts, and the problems encountered in the process integration of these components have been investigated. Ni/Au ohmic contacts with specific contact resistivities of 2.2 × 10−4 and 2.0 × 10−2 Ω cm2 were achieved on annealed, Mg-doped ([Mg] ∼ 5 × 1019 cm−3), p-type GaN layers that had been cleaned in HCl at 85 °C and on the backside of the SiC substrates after annealing in nitrogen, respectively. The emission intensity of the diodes increased with an increase in the number of Al0.06Ga0.94N/Al0.10Ga0.90N QWs and with the use of Si-doped n-type barrier layers. The highest intensities of the principle emission at 353 nm were measured at all values of the injection current in the device with a p-type carrier-blocking layer at the top of the QWs; this device also exhibited the highest values of light output power. Growth of an n-type carrier-blocking layer at the bottom of the QWs had an adverse effect on their characteristics. A broad peak centered at ∼540 nm exhibited yellow luminescence and was present in the spectra acquired from all the devices. This peak is attributed to absorption of the ultraviolet emission by and re-emission from the p-GaN and/or to the luminescence from the AlGaN within QWs by current injection.}, number={2-3}, journal={MATERIALS SCIENCE AND ENGINEERING B-SOLID STATE MATERIALS FOR ADVANCED TECHNOLOGY}, author={Park, JS and Reitmeier, ZJ and Fothergill, D and Zhang, XY and Muth, JF and Davis, RF}, year={2006}, month={Feb}, pages={169–179} }
 @article{park_fothergill_wellenius_bishop_muth_davis_2006, title={Origins of parasitic emissions from 353 nm AlGaN-based ultraviolet light emitting diodes over SiC substrates}, volume={45}, ISSN={["0021-4922"]}, DOI={10.1143/jjap.45.4083}, abstractNote={The effects of p-GaN capping layer and p-type carrier-blocking layer on the occurrence of parasitic emissions from 353 nm AlGaN-based light emitting diodes (LEDs) have been investigated. LEDs without a p-type Al0.25Ga0.75N carrier-blocking layer showed a shoulder peak at ∼370 nm due to electron overflow into the p-Al0.10Ga0.90N cladding layer and subsequent electron–hole recombination in the acceptor levels. Broad emission between 380 and 450 nm from LEDs having a p-GaN capping layer was caused by luminescence at 420 nm from the p-GaN capping layer, which was optically pumped by 353 nm UV emission from the quantum wells. Broad, defect-related luminescence centered at ∼520 nm was emitted from the AlGaN layers within the quantum wells.}, number={5A}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS}, author={Park, JS and Fothergill, DW and Wellenius, P and Bishop, SM and Muth, JF and Davis, RF}, year={2006}, month={May}, pages={4083–4086} }
 @article{park_fothergill_zhang_reitmeier_muth_davis_2005, title={Effect of carrier blocking layers on the emission characteristics of AlGaN-based ultraviolet light emitting diodes}, volume={44}, ISSN={["0021-4922"]}, DOI={10.1143/jjap.44.7254}, abstractNote={ 
  AlGaN-based thin film heterostructures suitable for ultraviolet light emitting diodes have been grown and fabricated into working devices with and without p-type and n-type AlGaN carrier-blocking layers at the top and the bottom of the quantum wells, respectively. The principal emission from each device occurred at 353 nm. The highest intensities of this peak were measured at all values of the injection current in the device with a p-type carrier-blocking layer at the top of the quantum well; this device also exhibited the highest values of light output power. Growth of an n-type carrier-blocking layer at the bottom of the quantum wells had an adverse effect on the light emitting diode characteristics. A broad peak centered at ∼540 nm exhibited yellow luminescence and was present in the spectra acquired from all the devices. This peak is attributed to absorption of the UV emission by and re-emission from the p-GaN and/or to the luminescence from the AlGaN within quantum wells by current injection. The intensity of this peak increased and saturated by the same order of magnitude as the intensity of the UV emission at 353 nm. 
  }, number={10}, journal={JAPANESE JOURNAL OF APPLIED PHYSICS PART 1-REGULAR PAPERS BRIEF COMMUNICATIONS & REVIEW PAPERS}, author={Park, JS and Fothergill, DW and Zhang, XY and Reitmeier, ZJ and Muth, JF and Davis, RF}, year={2005}, month={Oct}, pages={7254–7259} }
 @article{muth_zhang_cai_fothergill_roberts_rajagopal_cook_piner_linthicum_2005, title={Gallium nitride surface quantum wells}, volume={87}, number={19}, journal={Applied Physics Letters}, author={Muth, J. F. and Zhang, X. and Cai, A. and Fothergill, D. and Roberts, J. C. and Rajagopal, P. and Cook, J. W. and Piner, E. L. and Linthicum, K. J.}, year={2005} }