Analysis on the photo-carrier generation and photo-decay in metal-oxide semiconductors

김영훈 한국공업화학회 2016 한국공업화학회 연구논문 초록집 Vol.2016 No.0

Solution-processed metal-oxide semiconductors such as zinc oxide are now widely used in various energy harvesting devices such as organic solar cells and perovskite solar cells. However, since the oxide semiconductors can also show a high response to light illumination and possess persistent photoconductivity (PPC), it is important understand the photo carrier generation and decaying properties of oxide semiconductors. Here, we investigate the photoconductivity and photo-decaying porperties of various oxide semiconductor materials and structures such as indium gallium zinc oxide (IGZO), and a double-layered IZO/IGZO structure to identify the influence of channel materials and structures on the photocurrent and relaxation time of the device.

Oxide층의 두께와 위치 조절을 통한 oxido-VCSEL의 단일모드 동작반경 확장

김남길,김상배 대한전자공학회 2004 電子工學會論文誌-SD (Semiconductor and devices) Vol.41 No.9

oxide 층의 위치와 두께 조절을 통하여 oxide-VCSEL이 단일모드로 동작하는 활성영역의 반경을 확장하는 방법을 Self-consistent effective-index 방법을 이용하여 제시하였다. 이렇게 활성영역이 넓어지면 고속, 고신뢰도, 고출력 동작에 유리한 단일모드 VCSEL을 만들 수 있게 된다. 고출력을 위하여 단일모드로 동작하는 활성영역을 확대하는 방법을 하면 다음과 같다. 첫째 oxide 층은 활성층에서 멀리 떨어진 곳에 위치시켜야 한다 둘째, oxide 층은 얇게 만들어야 한다. 셋째, oxide층을 node에 위치시켜야 한다. 그리고 고출력을 위하여 p-DBR 쌍의 수를 줄이는 것은 단일모드 동작조건을 변화시키지 않는다. 이 방법을 사용하면 단일모드로 동작하는 oxide-aperture 크기를 3m% 이상 키울 수 있다. We have proposed a design methodology for large active-area single-mode VCSELS, which have higher reliability and output power, and are well-suited for high-speed operation. The key idea underlying the design methodology is to reduce the effective index difference between active and cladding regions by controlling the thickness and position of the oxide layer. The idea is confirmed by the self-consistent effective index method. By placing the oxide layer position properly, we can increase the radius of the oxide aperture for single-mode operation by 3 times.

Fabrication and characterization of p-n heterojunction with CoOx/IGZO oxide semiconductors

Juntae Ahn,Taeyoung Kim,Eun Kyu Kim 한국진공학회 2021 한국진공학회 학술발표회초록집 Vol.2021 No.2

Most of oxide semiconductors show n-type conduction, but there are some p-type materials such as copper oxide and cobalt oxide.[1,2] We fabricated oxide semiconductor based p-n heterojunction with p-CoOx and n-IGZO. The CoOx films were deposited by high vacuum RF sputtering system. IGZO films were sputtered. For Ohmic contacts, Au/Ti with thickness of 50 nm/3 nm and Al of 50 nm thickness were deposited on CoOx and IGZO layers, respectively, by a thermal evaporator. Thin film transistors and p-n heterojunctions of p-CoOx and m-IGZO films were fabricated and characterized.

Field Effect Transistors Based on One-Dimensional, Metal-Oxide Semiconducting Nanofiber Mats

유태희,황도경 한국물리학회 2019 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.74 No.9

Metal-oxide semiconductors are very promising alternatives to amorphous and polycrystalline Si semiconductors. In addition to thin-film metal-oxide semiconductors, nanostructured metal-oxide semiconductors have also attracted considerable attention due to their interesting physical properties for versatile potential applications. Here, we report on metal-oxide semiconducting (InZnO and HfInZnO) nanofiber mats prepared by electrospinning. Thermal gravimetric analyses (TGA) and X-ray diffraction (XRD) measurements were carried out so as to investigate the phase transition from as-spun metal precursor/polymer matrix composite nanofibers mats to metal-oxide nanofiber mats. We fabricated field effect transistor (FETs) based on InZnO and HfInZnO nanofiber mats, and both FETs showed proper $n$-type transfer and output characteristics. FETs based on InZnO nanofiber mats-based FETs exhibited superior device performance: negligible hysteresis, a decent electron mobility of 5.49 cm$^2$/Vs, and a good on/off current ratio of 10$^7$.

Efficient Suppression of Defects and Charge Trapping in High Density In–Sn–Zn–O Thin Film Transistor Prepared using Microwave-Assisted Sputter

Goh, Youngin,Ahn, Jaehan,Lee, Jeong Rak,Park, Wan Woo,Ko Park, Sang-Hee,Jeon, Sanghun American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.42

<P>Amorphous oxide semiconductor-based thin film transistors (TFTs) have been considered as excellent switching elements for driving active-matrix organic light-emitting diodes (AMOLED) owing to their high mobility and process compatibility. However, oxide semiconductors have inherent defects, causing fast transient charge trapping and device instability. For the next-generation displays such as flexible, wearable, or transparent displays, an active semiconductor layer with ultrahigh mobility and high reliability at low deposition temperature is required. Therefore, we introduced high density plasma microwave assisted (MWA) sputtering method as a promising deposition tool for the formation of high density and high-performance oxide semiconductor films. In this paper, we present the effect of the MWA sputtering method on the defects and fast charge trapping in In-Sn-Zn-O (ITZO) TFTs using various AC device characterization methodologies including fast I-V, pulsed I-V, transient current, low frequency noise, and discharge current analysis. Using these methods, we were able to analyze the charge trapping mechanism and intrinsic electrical characteristics, and extract the subgap density of the states of oxide TFTs quantitatively. In comparison to conventional sputtered ITZO, high density plasma MWA-sputtered ITZO exhibits outstanding electrical performance, negligible charge trapping characteristics and low subgap density of states. High-density plasma MWA sputtering method has high deposition rate even at low working pressure and control the ion bombardment energy, resulting in forming low defect generation in ITZO and presenting high performance ITZO TFT. We expect the proposed high density plasma sputtering method to be applicable to a wide range of oxide semiconductor device applications.</P>

Solution-processed indium–zinc oxide with carrier-suppressing additives

김동림,정웅희,김건희,김현재 한국정보디스플레이학회 2012 Journal of information display Vol.13 No.3

Metal oxide semiconductors were considered promising materials as backplanes of future displays. Moreover, the adoption of carrier-suppressing metal into indium–zinc oxide (IZO) has become one of the most important themes in the metal oxide research field. In this paper, efforts to realize and optimize IZO with diverse types of carrier suppressors are summarized. Properties such as the band gap of metal in the oxidized form and its electronegativity were examined to confirm their relationship with the metal’s carrier-suppressing ability. It was concluded that those two properties could be used as indicators of the carrier-suppressing ability of a material. As predicted by the properties, the alkali earth metals and early transition metals used in the research effectively suppressed the carrier and optimized the electrical properties of the metal oxide semiconductors. With the carrier-suppressing metals, IZO-based thin-film transistors with high (above 1 cm2/V · s) mobility, a lower than 0.6V/dec sub-threshold gate swing, and an over 3 × 106 on-to-off current ratio could be achieved.

Solution-processed indium-zinc oxide with carrier-suppressing additives

Kim, Dong Lim,Jeong, Woong Hee,Kim, Gun Hee,Kim, Hyun Jae The Korean Infomation Display Society 2012 Journal of information display Vol.13 No.3

Metal oxide semiconductors were considered promising materials as backplanes of future displays. Moreover, the adoption of carrier-suppressing metal into indium-zinc oxide (IZO) has become one of the most important themes in the metal oxide research field. In this paper, efforts to realize and optimize IZO with diverse types of carrier suppressors are summarized. Properties such as the band gap of metal in the oxidized form and its electronegativity were examined to confirm their relationship with the metal's carrier-suppressing ability. It was concluded that those two properties could be used as indicators of the carrier-suppressing ability of a material. As predicted by the properties, the alkali earth metals and early transition metals used in the research effectively suppressed the carrier and optimized the electrical properties of the metal oxide semiconductors. With the carrier-suppressing metals, IZO-based thin-film transistors with high (above $1cm^2/V{\cdot}s$) mobility, a lower than 0.6V/dec sub-threshold gate swing, and an over $3{\times}10^6$ on-to-off current ratio could be achieved.

Review of metal oxide semiconductors-based thin-film transistors for point-of-care sensor applications

임유승 한국정보디스플레이학회 2020 Journal of information display Vol.21 No.4

Recently, oxide semiconductors-based thin-film transistors have received much attention for biosensor platforms due to their high sensitivity, good chemical resistance, easy surface immobilizations of bioreceptors, and easy fabrication process with solution process or sputtering method. Unlike Si technologies, oxide semiconductors-based thin-film transistors can be fabricated easily and it is highly attractive to make simple sensor arrays. For long-term health-care monitoring, high sensitivity, selectivity, and low-cost chip should be considered. Regarding these issues, metal oxide semiconductors and thin-film transistors are good candidates. Here we address state-of-the-art research trends of biosensors with metal oxide semiconductors-bases thin-film transistors and discuss solution-processing and sputtering methods, separately.

Low Emissivity Property of Amorphous Oxide Multilayer (SIZO/Ag/SIZO) Structure

이상렬 한국전기전자재료학회 2017 Transactions on Electrical and Electronic Material Vol.18 No.1

Low emissivity glass for high transparency in the visible range and low emissivity in the IR (infrared) range wasfabricated and investigated. The multilayers were have been fabricated, and consisted of two outer oxide layers anda middle layer of Ag as a metal layer. Oxide layers were formed by rf sputtering and metal layers were formed usingby an evaporator at room temperature. SiInZnO (SIZO) film was used as an oxide layer. The OMO (oxide-metaloxide)structures of SIZO/Ag/SIZO were analyzed by using transmittance, AFM (atomic force microscopye), and XRD (X-raydiffraction). The OMO multilayer structure was designed to investigate the effect of Ag layer thickness on the opticalproperty of the OMO structure.

Atomic Layer Deposition of an Indium Gallium Oxide Thin Film for Thin-Film Transistor Applications

Sheng, Jiazhen,Park, Eun Jung,Shong, Bonggeun,Park, Jin-Seong American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.28

<P>Indium gallium oxide (IGO) thin films were deposited via atomic layer deposition (ALD) using [1,1,1-trimethyl-N-(trimethylsilyl)silanaminato]indium (InCA-1) and trimethylgallium (TMGa) as indium and gallium precursors, respectively, and hydrogen peroxide as the reactant. To clearly understand the mechanism of multicomponent ALD growth of oxide semiconductor materials, several variations in the precursorreactant deposition cycles were evaluated. Gallium could be doped into the oxide film at 200 C when accompanied by an InCA-1 pulse, and no growth of gallium oxide was observed without the simultaneous deposition of indium oxide. Density functional theory calculations for the initial adsorption of the precursors revealed that chemisorption of TMGa was kinetically hindered on hydroxylated SiOx but was spontaneous on a hydroxylated InOx surface. Moreover, the atomic composition and electrical characteristics, such as carrier concentration and resistivity, of the ALD-IGO film were controllable by adjusting the deposition supercycles, composed of InO and GaO subcycles. Thus, ALD-IGO could be employed to fabricate active layers for thin-film transistors to realize an optimum mobility of 9.45 cm(2)/(V s), a threshold voltage of -1.57 V, and a subthreshold slope of 0.26 V/decade.</P>