J.C. Schultz's research while affiliated with Palo Alto Research Center and other places

Publications (9)

Article
High-quantum-efficiency, lattice-mismatched, 1.0-eV GaInAs solar cells grown by organometallic vapor phase epitaxy have been developed for ultimate integration into AlGaAs/GaAs/GaInAs 3-junction, 2-terminal monolithic devices. The more standard n/p junction was replaced with an n-i-p structure in the GaInAs cell in order to increase the short-circu...
Article
Full-text available
Component efficiencies of 0.2/sq cm cells at approximately 100x AMO light concentration and 80 C temperatures are not at 15.3 percent for a 1.9 eV AlGaAs top cell, 9.9 percent for a 1.4 eV GaAs middle cell under a 1.9 eV AlGaAs filter, and 2.4 percent for a bottom 1.0 eV InGaAs cell under a GaAs substrate. The goal is to continue improvement in the...
Article
A Ga 0.8 In 0.2 As/GaAs thermally actuated optical switch has been demonstrated for unpolarized 1.08 μm light. Its measured on:off contrast ratio of 4.7 was produced electrically by changing the applied voltage from 0 to 3.2 V on a device with a 2.25‐μm‐thick Ga 0.8 In 0.2 As active layer. The ‘‘on’’ insertion loss was 3.8 dB. The on:off change in...
Conference Paper
The component cell milestone goals for an AM0 30% efficient, three-junction, two-terminal cell operating at 70 to 100°C at 100X concentration are 16% top cell, 11% middle cell, and 3% bottom cell. The best values measured so far at 80°C and 100X are 15.27% for a 1.9 eV AlGaAs top cell, 9.87% for a 1.4-eV GaAs middle cell, and 2.40% for a 1.0 eV InG...
Conference Paper
High-efficiency 1.0 eV GaInAs cells for ultimate integration into AlGaAs/GaAs/GaInAs 3-junction, 2-terminal monolithic devices are described. An n/p 1.0 eV GaInAs cell has been fabricated with a 4.7% (5.4%) solar conversion efficiency under 1-sun, 25°C, AM0 (AM1.5 G) conditions underneath a simulated GaAs cell. While this GaInAs cell had a AM0 J <s...
Conference Paper
A 27.6% efficiency measured under 1-sun, air mass 1.5-global illumination has been achieved in a two-terminal monolithic two-junction cascade solar cell consisting of an Al<sub>0.37</sub>Ga<sub>0.63</sub>As ( E <sub>g</sub>=1.93 eV) upper cell and a GaAs lower cell. This result represents the highest 1-sun efficiency to date. The component cells we...
Article
A 27.6 percent efficiency measured under 1-sun, air mass 1.5-global illumination has been achieved in a two-terminal monolithic two-junction cascade solar cell consisting of an Al0.37Ga0.63As (Eg = 1.93 eV) upper cell and a GaAs lower cell. This result represents the highest 1-sun efficiency to date. The component cells were electrically connected...
Article
This paper reviews recent progress at Varian to improve the efficiency of multijunction solar cells fabricated with GaAs-related materials. The most noteworthy achievement is the fabrication of a monolithic, two-terminal, two-junction AlGaAs/GaAs cell with a power conversion efficiency of 27.6% at 1 Sun, AM1.5 global. Recent results are presented f...
Conference Paper
High-efficiency AlGaAs n-on-p solar cells with bandgaps at 1.75 and 1.93 eV have been achieved in the MOVPE (metal-organic vapor-phase epitaxy) growth structure. Power conversion efficiencies of 17.2% and 15.2% have been obtained in the 1.75 and 1.93 eV AlGaAs cells, respectively. A comparison of experimental values of short-circuit current as a fu...

Citations

... The lattice mismatched GaInAs solar cell with a band gap of 0.7 eV grown on GaInP CGBs are fabricated, which achieves high quality metamorphic solar cells (Ryan 2014). The investigation is essential for a four-junctions solar cell development and other researches for this purpose have reported (Friedman et al. 2006;Schultz et al. 1993;Onno et al. 2016). This paper developed a metamorphic 0.67 eV Ga 0.48 In 0.52 As solar cell grown on AlGaInAs/GaAs metamorphic buffers. ...
... Solid-state dye sensitized solar cells (ssDSSCs) are also called third generation, organic (polymeric) or Grätzel (Gong 2017;Grätzel 2003;Sci et al. 2018;Sharma et al. 2018). The electron transport in these devices is carried out by diffusion, unlike the first (Blakers et al. 2013;Liu et al. 2018) and second-generation solar cells (Cariou et al. 2018;Macmillan et al. 1989), where transport is presented by an electric field. In recent years, ssDSSCs have gained attention due to advantages such as: simpler production techniques, non-toxic materials, lower production and material costs and more attractive designs compared to other types of solar cells (Sharma et al. 2015). ...
... Also, no carrier wafer is needed as in the IMM approach. A bi-facial epigrowth cell was first described by Varian [5] in 1990. They discuss an AlGaAs/GaAs/InGaAs tandem and clearly describe the idea of "farside" wafer growth, but did not actually make a bi-facial cell. ...