Preparation Of P-Type Cu₂O Films By Thermal Oxidation Method And Their Applications In Light-Emitting Devices

In nature,copper resources are very rich and their oxide has some advantages of low cost,nontoxicity,harmlessness,simple preparation and good chemical stability.Cu₂O is a new kind of p-type direct band gap semiconductor material.The long distance among the copper atoms results in no overlap between 3d and 4s orbital.Therefore,a system formed by a fully filled valence band and an empty conduction band structure in energy band,and the width is 2.2 eV.Cu₂O has high absorption coefficient and photoelectric conversion efficiency in the visible region,leading to wide application prospect in the information functional materials,solar cell and photocatalyst.Meanwhile,Cu₂O has unique property with direct band gap,which is considered to be potential light-emitting materials.However,the study of Cu₂O luminescent properties are limited.This paper focuses on the preparation of high-quality stable p-type Cu₂O film,and detailedly researches the effect of the preparation conditions on physical properties.On this basis,the optimized Cu₂O film as the hole injection layer embedded in the Au/MgO/ZnO matal-insulator-semiconductor?MIS?heterojunction device,changed the embedded position of Cu₂O film,and effectively improved the device performance of electroluminescence.The specific research work are as follows:?1?Using the high temperature?1050??and low temperature?200 to 400??thermal oxidation method,Cu₂O film was prepared on the deposition of metal Cu film,and compared to explore the oxidation kinetics by changing the oxidization time.Through the analyzing of the quality of the film crystallization,element content and composition,photoluminescence,optical reflection/absorption spectra and the electrical parameters,it was found that the temperature and oxidation time respectively controlled 200? and 3 h,a pure phase,stable and good conductive Cu₂O film obtained.The resistivity,carrier concentration and mobility was15.5·?·cm,4.17×10¹⁷cm^-3and 1.1 cm²/Vs,respectively.The results show that the Cu₂O film with good photoelectric performance can obtain under the condition of low temperature?200??.?2?The optimized p-type Cu₂O film will be introduced to Au/MgO/ZnO heterojunction devices,building the Cu₂O/MgO/ZnO?forward?and ZnO/MgO/Cu₂O?inverted?MIS heterojunction devices with two different configurations,and exploring the influence of the introduction of Cu₂O layer on the device performance.The results show that,for Cu₂O/MgO/ZnO?forward?heterostructure device,p-type Cu₂O film as the hole injection layer increased the intrinsic carrier concentration of MgO layer,promoting production efficiency of holes in the collision ionization process.On the basis of the enhanced ultraviolet emission of MIS device,it is obtained low-threshold random laser from the ZnO layer.For ZnO/MgO/Cu₂O?inverted?heterostructure device,due to the introduction of Cu₂O,composite electroluminescent spectra with the near band-gap edge emission of Cu₂O,copper vacancy defect emission,ZnO ultraviolet emission and deep level defect emission of ZnO obtained,that is,the similar white-light emission from the device was obtained,which is widened the ZnO MIS heterojunction electroluminescence range.