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HL: Halbleiterphysik

HL 34: Impurities/Amorphous semiconductors

HL 34.5: Vortrag

Mittwoch, 29. März 2006, 18:15–18:30, BEY 154

Structuring and characterisation of electronic phase change memories — •Michael Woda, Henning Dieker, Christoph Steimer, and Matthias Wuttig — I. Insitute of Physics (IA), RWTH Aachen University, 52056 Aachen, Germany

Chalcogenide based phase change materials exhibit an optical contrast between their amorphous and crystalline phase which can be switched rapidly and reversibly by laser pulses. The change in reflectivity is used in optical data storage applications such as CD and DVD.

In addition phase change alloys show a remarkable change in resistivity of several orders of magnitude. Phase change memories (or PCRAM, Ovonic memory) utilize this electronic contrast and use different short current pulses for reading and writing. It is a promising candidate to compete with existing non volatile flash memory applications.

As a characteristic feature threshold switching occurs at an applied voltage when the material is in the low conductive amorphous state. Threshold switching is necessary for phase transitions at low operating voltages. For a successful choice of material and memory development a good understanding of the switching effect has to be achieved.

Different ways of structuring phase change memory bits are presented. Electric characterization methods for determining the threshold voltage are shown. An outlook how to clarify the physical origin of the threshold switching is given.