Study Of ZnO-based MIS Heterostructure Ultraviolet Light Emitting Device On Metal Copper Substrate

With the rapid development of information technology, optoelectronic technology hasgradually become the foundation for network communication technology. As the core of theinformation technology, the semiconductor laser promotes the CD-ROM-based informationstorage technology. Because the storage density of the disc is inversely proportional to thewavelength of the laser, we should use a short wavelength semiconductor laser to increase thestorage density of the disc.Semiconductor ZnO has a wide band gap of3.37eV and a large excition binding energyof60meV, which favors a high-efficiency excitonic emission at high temperature. Therefore,ZnO become a promising candidate material for short-wavelength light emitting device.However, stable and high quality p-type ZnO still hinders the development of ZnOhomojunctions. Therefore, heterojunctions have been paid great efforts in the research of ZnObased light emitting devices. Recently, metal-insulator-semiconductor (MIS) heterojucntionshave attracted more attentions. On the other hand, most ZnO based light emitting devices usedconventional substrates such as GaN, Al2O3and Si, which have bad heat dissipation that thedevice performance may be degraded. In our experiment, metal Cu is used as the substrate inZnO-based light emitting devices, which is known as an ideal choice due to its high thermalconductivity. Besides, the work function of Cu (~4.65eV) is close to the Fermi level of ZnO,and it has been reported that an ohmic contact can be formed between Cu and ZnO.The primary contents and conclusions of our research work are decrisbed as follows:(1) Au/MgO/ZnO lasing diode is directly achieved on copper substrate by inserting ananti-oxidation buffer layer. The anti-oxidation buffer layer can effectively inhibit theoxidation of the Cu substrate. And this anti-oxidation ZnO layer grown in Ar is highlyconductive, more electrons could be supplied and injected into the active region underworking bias. Moreover, this oxygen-deficient ZnO layer also performs as a buffer layer toimprove the optical and crystalline quality of ZnO epitaxial layer.(2) The high thermal conductivity of copper substrate reduces the device thermal effect.Nearly no relative shift is observed between ZnO electroluminescence and photoluminescencepeaks and among the electroluminescence emissions with the injection current increasing.Besides, the employment of copper substrate reduces the device series resistance to produceless joule heat.(3) Our ZnO lasing diode is determined as random laser mode and further discussed bymicro-structural characterization.