| Summary: | 碩士 === 國立交通大學 === 電子工程系 === 89 === An ITO/superlattice/p-Si tunnel diode used as a light-emitting device was made on the Si substrate. The superlattice (SL) is formed by alternatively depositing ITO and Al2O3 materials, and the thickness of each SL layer is in the range of 10~20Å. At a forward bias -3V, strong and uniform electroluminescence (EL) from SL tunnel diode is detected, and the emitted light is mainly located in the infrared region. The light intensity from SL tunnel diode is three orders of magnitude larger than hot-carrier induced light emission in MOSFETs, and near 10000 greater than gate-injected MOS tunnel diode. At higher biasing conditions (>-7V), the high-energy tail can even be seen by naked eyes. We thought electrons from the minibands of SL tunnel into Si substrate and relax their extra energy via radiative recombination and/or impact ionization. The SL structure is used to elevate the injecting electron energy and reduce electric field inside Al2O3 layers. The use of Al2O3 arises from the advantages of its good dielectric integrity and high permittivity. Better hole confinement and larger extra momentum of carriers are found in the Al2O3 SL tunnel diodes. The momentum conservation for radiative recombination is easier to achieve, thus EL from the Si substrate will be enhanced.
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