Dresden 2011 – wissenschaftliches Programm

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HL: Fachverband Halbleiterphysik

HL 5: Innovative Systems and Devices

HL 5.6: Vortrag

Montag, 14. März 2011, 11:45–12:00, POT 06

Si-InAs heterojunction Esaki tunnel diodes with high current densities — •Cedric Bessire, Mikael Björk, Heinz Schmid, Kirsten Moselund, Hesham Ghoneim, Siegfried Karg, and Heike Riel — IBM Research Zurich, Säumerstrasse 4, 8803 Rüschlikon, Switzerland

The tunnel field effect transistor (TFET) is considered to be one of the most promising candidates for low power operation because its turn-on characteristics can be steeper than that of conventional FETs, which could allow drastic scaling of the supply voltage. However, to date TFET implementations show poor performance of the drive current compared to conventional CMOS devices due to low tunneling probability. For high currents in TFETs degenerated semiconductors and abrupt interfaces are needed. This can be evaluated by Esaki tunnel diodes that indicate the limits of the drive current.

We report on Si-InAs heterojunctions with high tunnel current densities and negative differential resistance region in low forward bias. The p-n diodes were fabricated by growing InAs nanowires in oxide mask openings on silicon substrates. At substrate doping concentrations of 1e16 and 1e19 cm-3, conventional diode characteristics were obtained, from which a valence band offset between Si and InAs of 130 meV was extracted. For a substrate doping of 4e19 cm-3, heterojunction tunnel diode characteristics were obtained showing current densities in the range of 50 kA/cm2 at 0.5 V reverse bias. In addition, in situ doping of the InAs wires was performed using disilane to further boost the tunnel currents up to 100 kA/cm2 at 0.5 V reverse bias.