Issue 10 Volume 41 May 16, 2003

The atomic layer epitaxy (ALE) technique was used to grow thin films of binary metal oxides Al2O3, Ga2O3 and La2O3,
and ternary metal oxides LaNiO3, LaCoO3, LaAlO3, and LaGaO3. In addition, another type of mixed-oxide, viz.
phosphorus-doped Al2O3 was studied. The binary oxides Ga2O3 and La2O3 and all the ternary oxides were deposited by the
ALE method for the first time. New ALE processes were developed for the undoped and doped Al2O3 films. The thin films
were characterized by a wide range of methods for structural and surface analysis, including XRD, FTIR, XPS, AFM, XRF,
RBS, TOF-ERDA, and SIMS. A review of previous work on these trivalent metal oxide thin films is presented by way of
background.
NTIS
Deposition; Atomic Layer Epitaxy; Thin Films; Metals
20030036989 NASA Goddard Space Flight Center, Greenbelt, MD, USA
Evaluation of Data Retention and Imprint Characteristics of FRAMs Under Environmental Stresses for NASA
Applications
Sharma, Asbok K.; Teverovsky, Alexander; Dowdy, Terry W.; Hamilton, Brett; [2002]; 8 pp.; In English; NVMTS 2002
Conference, 4-8 Nov. 2002, Honolulu, HI, USA; Original contains black and white illustrations; No Copyright; Avail: CASI;
A02, Hardcopy
A major reliability issue for all advanced nonvolatile memory (NVM) technology devices including FRAMs is the data
retention characteristics over extended period of time, under environmental stresses and exposure to total ionizing dose (TID)
radiation effects. For this testing, 256 Kb FRAMs in 28-pin plastic DIPS, rated for industrial grade temperature range of -40
C to +85 C, were procured. These are two-transistor, two-capacitor (2T-2C) design FRAMs. In addition to data retention
characteristics, the parts were also evaluated for imprint failures, which are defined as the failure of cells to change from a
‘preferred’ state, where it has been for a significant period of time to an opposite state (e.g., from 1 to 0, or 0 to 1). These 256
K FRAMs were subjected to scanning acoustic microscopy (C-SAM); 1,000 temperature cycles from -65 C to +150 C; high
temperature aging at 150 C, 175 C, and 200 C for 1,000 hours; highly accelerated stress test (HAST) for 500 hours; 1,000
hours of operational life test at 125 C; and total ionizing dose radiation testing. As a preconditioning, 10 K read/write cycles
were performed on all devices. Interim electrical measurements were performed throughout this characterization, including
special imprint testing and final electrical testing. Some failures were observed during high temperature aging test at 200 C,
during HAST testing, and during 1,000 hours of operational life at 125 C. The parts passed 10 Krad exposure, but began
showing power supply current increases during the dose increment from 10 Krad to 30 Krad, and at 40 Krad severe data
retention and parametric failures were observed. Failures from various environmental group testing are currently being
analyzed.
Author
Ferroelectricity; Random Access Memory; Radiation Effects; Radiation Dosage; Ionizing Radiation; Radiation Tolerance;
Microelectronics; Accelerated Life Tests
20030037007 National Renewable Energy Lab., Golden, CO
GaNPAs Solar Cells Lattice-Matched to GaP
Geisz, J. F.; Friedman, D. J.; Kurtz, S.; May 2002; 12 pp.; In English
Report No.(s): DE2002-15000994; No Copyright; Avail: Department of Energy Information Bridge
This conference paper describes the III-V semiconductors grown on silicon substrates are very attractive for lower-cost,
high-efficiency multijunction solar cells, but lattice-mismatched alloys that result in high dislocation densities have been
unable to achieve satisfactory performance. GaNxP1-x-yAsy is a direct-gap III-V alloy that can be grown lattice-matched to
Si when y = 4.7x - 0.1. We propose the use of lattice-matched GaNPAs on silicon for high-efficiency multijunction solar cells.
We have grown GaNxP1-x-yAsy on GaP (with a similar lattice constant to silicon) by metal-organic chemical vapor phase
epitaxy with direct band-gaps in the range of 1.5 to 2.0 eV. We demonstrate the performance of single junction
GaNxP1-x-yAsy solar cells grown on GaP substrates and discuss the prospects for the development of monolithic high
efficiency multijunction solar cells based on silicon substrates.
NTIS
Semiconductors (Materials); Solar Cells; Substrates; Gallium Phosphides; Gallium Arsenides; Crystal Lattices
20030037053 National Renewable Energy Lab., Golden, CO
Deep-Level Transient Spectroscopy in InGaAsN Lattice-Matched
Johnston, S. W.; Ahrenkiel, R. K.; Friedman, D. J.; Kurtz, S. R.; May 2002; 12 pp.; In English
Report No.(s): DE2002-15000982; No Copyright; Avail: Department of Energy Information Bridge
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