Volume 96, Issue 5, 01 September 2004
Index of content:
- DEVICE PHYSICS (PACS 85)
The energy-fine structure of multiple quantum wells grown at different temperatures and postgrown annealed96(2004); http://dx.doi.org/10.1063/1.1774258View Description Hide Description
We report photoreflectance investigations of the energy-fine structure of multiple quantum wells(MQWs) grown at different temperatures and postgrown treated by rapid thermal annealing(RTA). A “splitting” of the ground and excited QW transitious due to the presence of different nitrogen nearest-neighbor environments, i.e., short-range-order clusters, has been observed. The RTA induces a nitrogen redistribution between the five possible configurations and thus leads to a blueshift of QW transitions. The magnitude of the blueshift and its dependence on the growth temperature and annealing temperature are investigated in this paper.
96(2004); http://dx.doi.org/10.1063/1.1771825View Description Hide Description
For electromigration in short aluminuminterconnects terminated by tungsten vias, the well known “short-line” effect applies. In a similar manner, for longer lines, early failure is determined by a critical value for the length of polygranular clusters. Any cluster shorter than is “immortal” on the time scale of early failure where the figure of merit is not the standard value (the time to 50% failures), but rather the total probability of early failure, . is a complex function of current density,linewidth, line length, and material properties (the median grain size and grain size shape factor ). It is calculated here using a model based around the theory of runs, which has proved itself to be a useful tool for assessing the probability of extreme events. Our analysis shows that is strongly dependent on , and a change in from 0.27 to 0.5 can cause an order of magnitude increase in under typical test conditions. This has implications for the web-based two-dimensional grain-growth simulator MIT/EmSim, which generates grain patterns with , while typical as-patterned structures are better represented by a in the range 0.4 – 0.6. The simulator will consequently overestimate interconnect reliability due to this particular electromigration failure mode.
96(2004); http://dx.doi.org/10.1063/1.1776627View Description Hide Description
The effect of -doping on the microstructure and magnetic properties of thin layers has been employed to construct all -electrode magnetic tunnel junctions that displayed the tunneling magnetoresistance (TMR) effect. Using low nitrogen doses, a reduction in coercivity was achieved due to grain refinement, without a concurrent decrease in the saturationmagnetization of the films caused by the formation of crystalline iron nitride phases. It was demonstrated that this -induced grain refinement can be applied beneficially to control the switching field of the “free” layer in magnetic trilayer structures. In general the ability to control magnetic softness without reducing saturationmagnetization will prove important for incorporating high spin-polarized materials into spin valves and TMR devices.