No abstract

No abstract

A 2H-SiC thin film has been grown on a 6H-SiC substrate by laser ablation using an excimer laser. The deposition of 2H-SiC film occurred in a high vacuum system (≊10−6 Torr) with the substrate temperature near 1200 °C. Plan-view and cross-sectional transmission electron microscopy (TEM) were used to measure the lattice parameters and to identify the polytype. Cross-sectional TEM images clearly show the symmetry of the film as c-axis oriented 2H-SiC containing columnar grains with an average diameter of 20 nm and a length of 100 nm.

No abstract

Theoretical calculations have shown that highest‐efficiency III–V multi‐junction solar cells require alloy structures that cannot be grown on a lattice‐matched substrate. Ever since the first demonstration of high‐efficiency metamorphic single‐ junction 1.1 and 1.2 eV InGaAs solar cells, interest has grown in the development of multi‐junction cells of this type, using graded buffer layer technology. Essential Research Incorporated (ERI) is currently developing a dual‐junction 1.6 eV InGaP/1.1 eV InGaAs tandem cell (projected practical air‐mass zero (AM0), one‐sun efficiency of 27%, and 100‐sun efficiency of 31.1%) under a Ballistic Missile Defense Command (BMDO) SBIR Phase II program. A second ongoing research effort involves the development of a 2.1 eV AlGaInP/1.6 eV InGaAsP/1.2 eV InGaAs triple‐junction concentrator tandem cell (projected practical AM0 efficiency 36.5% under 100 suns) under a SBIR Phase II program funded by the Air Force. We are in the process of optimizing the dual‐junction cell performance. For the triple‐junction cell, we have developed the bottom and the middle cell, and are in the process of developing the layer structures needed for the top cell. A progress report is presented in this paper. Copyright © 2002 John Wiley & Sons, Ltd.