Modulation And Investigation On The Photoelectric And Sensing Properties Of IGZO Thin Film Using 2D BP

In the past few decades,metal oxide(M-O)semiconductors have been widely studied due to their excellent properties in display devices,electronic devices,optoelectronic devices and biomedical sensors.Indium gallium zinc oxide(a-IGZO)is the most representative M-O material with a wide band gap of 3.8 e V,high mobility,low-temperature-preparation and high stability.The photodetector based on IGZO on the flexible substrate has been widely studied,but the requirements in different occasions are different for the sensitivity of phototransistor in practical applications.For the photodetector in the range of ordinary visible light,devices need to have a very strong response to the light.But for the military detectors in the space or national defense,the devices are expected to be insensitive in visible light or almost unresponsive to maintain stability.Therefore,it is very important to control the responsibility of phototransistors based on IGZO.At present,a series of means for regulation about IGZO optoelectronic devices are reported,the method of constructing heterojunction by using different kinds of two-dimensional materials has been widely studied and achieved some accomplishments due to the characteristics of simple operation and wide range of regulation.However,in the current methods reported,it is impossible to achieve the systematic regulation of IGZO photocurrent through a kind of single material.Based on that,this paper successfully enhanced the photoresponsibility of IGZO from 0.05 A/W to 0.3 A/W at the wavelength of 447 nm through different modification methods of two-dimensional black phosphorus(BP).Several different structures modified by BP were researched for humidity sensing,and the main mechanism of regulation in photocurrent and humidity sensing were analyzed from the perspective of energy band structure and surface charge transfer.The main contents of this paper are as follows:1.The photoelectric performance of IGZO transistors can be controlled by building different contact modes between 2D BP and IGZO thin films.Firstly,the specific process of preparing IGZO in our laboratory is introduced,and the construction of photoelectric test system is also introduced.The relatively optimal parameters of IGZO photoelectric transistor are found by changing the thickness and channel width of the film.Then,through the introduction of the way of BP and BP/BN modification a variety of heterogeneous structures are constructed,including the IGZO,IGZO/BP(I)(BP contacts with electrodes),IGZO/BP(II)(BP is not in contact with the electrodes),IGZO/BN/BP(I)(BN covers the channel only)and the IGZO/BN/BP(II)(BN covers electrodes and the channel),measure and contrast the optoelectronic properties of several kinds of structures,the regulation of the IGZO photocurrent from 0 to 2 ?A is achieved in the wavelength of 447 nm.Finally,the mechanism of the change of photocurrent is analyzed by using the energy band theory.It is considered that the charge transfer of the carriers between IGZO and BP occurs after tunneling through the ultra-thin BN,which leads to the enhancement of the photocurrent.2.By changing the size of the IGZO film and the material of the electrodes of the device,the BP-IGZO heterojunction was prepared.Firstly,by changing the thickness of the BP film,the improvement of four orders of magnitude in the rectification ratio was achieved.Then,the structure of the PN junction was characterized by OM,AFM and SEM,and the integrity of the interface was confirmed.Finally,the photoelectric properties of BP-IGZO PN junction were studied from different positions,different laser powers and different polarities of bias.3.The humidity sensing performance of IGZO devices on Si/Si O2 substrates and flexible PET substrates is improved by 2D BP modification.Firstly,the characteristics of humidity sensing of two kinds of IGZO devices on substrates(with or without 2D BP modification)were systematically studied,and it was found that the sensing performance was enhanced after the introduction of BP.Then,the influence of the substrate on the humidity sensing is compared.It is found that the humidity sensing performance on the flexible PET substrate is better,and the sensitivity can reach 40%.Finally,the above phenomena are analyzed from the view of interface.It is concluded that the improvement of humidity sensing performance after the introduction of BP is due to the larger specific surface area and the sensitivity to humidity.The reason for the higher sensitivity on the flexible substrate is that the substrate has larger effective contact area with the sample,making water molecules easier to gather on the surface and causes charge transfer.