Simulation And Characterization Of ZnSe/BeTe Resonant Tunneling Diode On Silicon

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Title: Simulation And Characterization Of ZnSe/BeTe Resonant Tunneling Diode On Silicon
Author: Davis, Moshe
Abstract: ZnSe /BeTe resonant tunneling diodes were grown on silicon with a ZnxBe1 -xTe buffer layer using MBE (Molecular Beam epitaxy ) .These devices were processed and characterized . The devices showed multiple NDR (negative differential resistance ) regions at room temperature with PVR (Peak to valley ratios ) between 1 .01 to 1 .23 . Variations to the structure were made in growth and their corresponding current -voltage characteristics were studied . The ZnSe /BeTe resonant tunneling diode showed asymmetrical current voltage characteristics for positive and negative biases . The sources of asymmetry were investigated during fabrication and with the help of simulations . The Al /ZnSe contact was confirmed to be ohmic contact when the aluminum is deposited in -situ in the MBE chamber . Low temperature measurements were done on the samples and additional NDR regions were observed at 3 .2K . NEMO (Nano -electronic modeling ) a quantum device simulator was used to model the experimental current -voltage characteristics of the device . The sp3s* tight binding parameters which define the band structure of a material were implemented in NEMO and optimized to get the desired band offsets . The addition of no -common atom interfaces of BeSe and ZnTe to the ZnSe /BeTe hetero -structure were found to qualitatively model the experimental characteristics . The other sources of asymmetry in current -voltage characteristics such as non -equivalent interfaces , asymmetric doping and asymmetric thickness were studied using NEMO .The most important factor contributing to the asymmetry in NEMO current -voltage simulations were found to be the alternating interfaces of BeSe and ZnTe . Thermally assisted tunneling and the effect of Fermi -level raising on PVR were studied using NEMO .
URI: http : / /hdl .handle .net /10106 /36
Date: 2007-08-23

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Simulation And Characterization Of ZnSe/BeTe Resonant Tunneling Diode On Silicon. Available electronically from http : / /hdl .handle .net /10106 /36 .

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