Effect of Annealing and Oxygen Flow on the Optical Properties of ZnO Thin Film Grown by Using Pulsed Laser Deposition

이천,김재홍,Sung-Kwon Shin 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.5

ZnO thin films have been deposited on (001) sapphire substrates by using a pulsed laser deposition (PLD) technique with a Nd:YAG laser at a wavelength of 266 nm. The deposition of the films was performed at substrate temperatures in the range of 300 ∽ 450 ℃ and at a flow rate of 100 ∽ 700 sccm before annealing treatment in an oxygen ambient. In order to investigate the effect of the annealing treatment on lms deposited at a fixed oxygen pressure of 350 sccm and a substrate temperature of 400 ℃, we annealed films at various temperatures after deposition. After annealing treatment in the oxygen ambient, the structural properties of the ZnO thin films were characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of lms were also characterized by using photoluminescence (PL). The crystallinity of the ZnO thin film was improved with increased annealing temperature. As the post-annealing temperature was increased, the intensity of the UV peak broadened and decreased. In particular, the position of the visible luminescence peak shifted to a shorter wavelength, and its intensity was increased at 800 ℃. ZnO thin films have been deposited on (001) sapphire substrates by using a pulsed laser deposition (PLD) technique with a Nd:YAG laser at a wavelength of 266 nm. The deposition of the films was performed at substrate temperatures in the range of 300 ∽ 450 ℃ and at a flow rate of 100 ∽ 700 sccm before annealing treatment in an oxygen ambient. In order to investigate the effect of the annealing treatment on lms deposited at a fixed oxygen pressure of 350 sccm and a substrate temperature of 400 ℃, we annealed films at various temperatures after deposition. After annealing treatment in the oxygen ambient, the structural properties of the ZnO thin films were characterized by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). The optical properties of lms were also characterized by using photoluminescence (PL). The crystallinity of the ZnO thin film was improved with increased annealing temperature. As the post-annealing temperature was increased, the intensity of the UV peak broadened and decreased. In particular, the position of the visible luminescence peak shifted to a shorter wavelength, and its intensity was increased at 800 ℃.

Annealing Effects on Charge Trap Flash with TAHOS Structure

Min Suk Song,Hwiho Hwang,Junsu Yu,Sungmin Hwang,Hyungjin Kim 대한전자공학회 2024 Journal of semiconductor technology and science Vol.24 No.4

Flash memory is gaining attention due to its scalability, high reliability, and multilevel capabilities. This study investigated the charge trapping characteristics of high permittivity HfO₂ films with Al₂O₃ as a blocking oxide. TAHOS (TiN-Al₂O₃-HfO₂-SiO₂-Si) structure capacitors were fabricated to explore the annealing effects for charge trap flash (CTF) memory device applications. HfO₂, serving as a charge trapping layer, offers the advantage of achieving a wide memory window owing to its high trap density. In this work, various characteristics related to memory cells were examined based on annealing temperature and gas type. Post-deposition annealing (PDA) was conducted from 900 °C to 1050 °C and forming gas annealing (FGA) was performed at 450 °C for 10 minutes using H₂ gas. We analyzed the memory window and flat-band voltage distributions by measuring C-V characteristics. These results suggest that optimal annealing conditions can be helpful to improve memory characteristics in TAHOS stacked flash memories.

Post-deposition annealing effects on the transparent conducting properties of anatase Nb:TiO₂ films on glass substrates

Wang, C.,Li, J.,Dho, J. Elsevier 2014 Materials science & engineering. B, Advanced funct Vol.182 No.-

Five percent Nb-doped TiO<SUB>2</SUB> (Nb:TiO<SUB>2</SUB>) films on glass substrates were prepared with pulsed laser deposition in 10mTorr at room temperature, and then, they were annealed at various temperatures from 250 to 550<SUP>o</SUP>C in vacuum (<10<SUP>-5</SUP>Torr). The X-ray diffraction data suggest that the as-prepared amorphous Nb:TiO<SUB>2</SUB> film on glass was transformed to the (101) oriented anatase phase above ~350<SUP>o</SUP>C. For the anatase Nb:TiO<SUB>2</SUB> samples, the temperature dependence of the resistance exhibited a metallic behavior. As the post-deposition annealing temperature increased up to 550<SUP>o</SUP>C, the resistivity (~3.9x10<SUP>-4</SUP>Ωcm) was minimum at 450<SUP>o</SUP>C while the Hall mobility (2.6cm<SUP>2</SUP>/(Vs)) and carrier density (4.7x10<SUP>21</SUP>cm<SUP>-3</SUP>) were maximum. The optical transmittance in the visible light range was about 70-80%, and the optical band gaps gradually decreased from 3.64 to 3.28eV as the post-deposition annealing temperature increased.

Current Transport Analysis of ZrO2 Thin Films: Effects of Post-deposition Annealing

정희준 한국물리학회 2014 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.65 No.11

We report on the effects of post-deposition annealing on the electrical properties and the dielectricperformance of atomic layer-deposited ZrO2 thin films investigated by using capacitance-voltageand current-voltage measurements. ZrO2 films crystallized by post-deposition annealing in vacuumshowed an enhanced dielectric constant and energy band gap, but the leakage current was increased. The Poole-Frankel and the trap assisted tunneling mechanisms were considered to be the majorleakage current conduction processes and the charge trap energy level was reduced from 1.09 −1.13 eV to 0.81 − 0.84 eV by post-deposition annealing. The increase in the leakage current in thecrystallized films can be explained by considering structural defect relaxation or grain boundaryformation.

Effects of Post-deposition Annealing Temperature on the Structure and Photoluminescence of Zinc Germanate Thin Films Doped with Manganese

Kyung Ho Yoon,김주한 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.5

The effects of post-deposition annealing temperature on the structure and the photoluminescence of thin-film zinc germanate doped with manganese (Zn_2GeO_4:Mn) were investigated. The Zn_2GeO_4:Mn films were deposited by radio-frequency (RF) magnetron sputtering, followed by postdeposition annealing at temperatures of 700 – 1000 ℃. As-deposited Zn_2GeO_4:Mn films had an amorphous structure with a smooth surface morphology. The Zn_2GeO_4:Mn films became crystalline after annealing at 700 ℃, and the crystallinity of the films was continuously improved up to 1000 ℃. Annealed Zn_2GeO_4:Mn films had a polycrystalline rhombohedral structure with no preferred crystallographic orientation of the crystallites. The lattice parameters of the rhombohedral Zn_2GeO_4 phase were measured to be a = 14.228 °A and c = 9.525 °A. Formation of secondary phases, such as ZnGeO3 and GeO2, was observed in the films annealed at 1000 ℃. The photoluminescence (PL) spectra of the annealed Zn_2GeO_4:Mn films showed broad-band emissions with a peak maximum around 535 nm in the green range. The PL emission intensity was enhanced as the annealing temperature was increased, resulting from improved crystallinity of the Zn_2GeO_4:Mn films. A broadening of the PL spectrum was observed for films annealed at 1000 ℃ due to the formation of secondary phases.

화학선 증착법에 의한 $MgF_2$ 박막제조

박보현,백성기 한국세라믹학회 1996 한국세라믹학회지 Vol.33 No.3

We invesgated the fesibility of thin films deposition by pyrolysis of metalorganic precursors using chemical beam deposition (CBD) process. We attempted to understand the effects of deposition variables such as substrate temperature operating pressure effusion cell temperature and H2 partial pressure on the properties of MgF2 grown by CBD. Mg(tfac)2 was used as a precursor. MgF2 thin films were always grown in an amorphous state and crystallized bypost-annealing. he higher the substrate temperature and the lower the operating pressure the less the impurities I the deposited MgF2 thin films. H2 gas has to be supplied for the pyrolitic reaction of Mg(tfac)2 decomposition. MgF2 films annealed in H2 have lower C impurity than those annealed in O2. But their crysatllinity was independent of annealing atmosphere. The optimum conditions for the prepara-tion of MgF2 films by CBD process were as following : The substrate temperature 55$0^{\circ}C$ the operating pressure 10-4 torr; effusion cell temperature 21$0^{\circ}C$ the percentage of H2 100% Post-annealing in H2 gas was required to remove residual carbon and to form MgF2 crystalline phase.

Effects of post-deposition annealing on sputtered SiO₂/4H-SiC metal-oxide-semiconductor

Lee, Suhyeong,Kim, Young Seok,Kang, Hong Jeon,Kim, Hyunwoo,Ha, Min-Woo,Kim, Hyeong Joon Elsevier 2018 Solid-state electronics Vol.139 No.-

<P><B>Abstract</B></P> <P>Reactive sputtering followed by N<SUB>2</SUB>, NH<SUB>3</SUB>, O<SUB>2</SUB>, and NO post-deposition annealing (PDA) of SiO<SUB>2</SUB> on 4H-SiC was investigated in this study. The results of ellipsometry, an etching test, and X-ray photoemission spectroscopy showed that N<SUB>2</SUB> and NH<SUB>3</SUB> PDA nitrified the SiO<SUB>2</SUB>. Devices using N<SUB>2</SUB> and NH<SUB>3</SUB> PDA exhibited a high gate leakage current and low breakdown field due to oxygen vacancies and incomplete oxynitride. SiO<SUB>2</SUB>/4H-SiC MOS capacitors were also fabricated and their electrical characteristics measured. The average breakdown fields of the devices using N<SUB>2</SUB>, NH<SUB>3</SUB>, O<SUB>2</SUB>, and NO PDA were 0.12, 0.17, 4.71 and 2.63 MV/cm, respectively. The shifts in the flat-band voltage after O<SUB>2</SUB> and NO PDA were 0.95 and −2.56 V, respectively, compared with the theoretical value. The extracted effective oxide charge was −4.11 × 10<SUP>11</SUP> cm<SUP>−2</SUP> for O<SUB>2</SUB> PDA and 1.11 × 10<SUP>12</SUP> cm<SUP>−2</SUP> for NO PDA. NO PDA for 2 h at 1200 °C shifted the capacitance–voltage curve in the negative direction. The oxygen containing PDA showed better electrical properties than non-oxygen PDA. The sputtering method described can be applied to 4H-SiC MOS fabrication.</P> <P><B>Highlights</B></P> <P> <UL> <LI> SiO<SUB>2</SUB> film on 4H-SiC was investigated using reactive sputtering and post-deposition annealing. </LI> <LI> PDA decreased the etching rate and induced densification of SiO<SUB>2</SUB>. </LI> <LI> XPS results demonstrated nitridation of SiO<SUB>2</SUB>/4H-SiC after N<SUB>2</SUB> and NH<SUB>3</SUB> PDA. </LI> <LI> O<SUB>2</SUB> and NO PDA improved the leakage current as well as the breakdown field. </LI> </UL> </P>

Reduction of defect states in atomic-layered HfO₂ film on SiC substrate using post-nitridation annealing

Kwon, Sera,Kim, Dae-Kyoung,Cho, Mann-Ho,Chung, Kwun-Bum Elsevier 2018 THIN SOLID FILMS - Vol.645 No.-

<P><B>Abstract</B></P> <P>The changes of the defect states below the conduction band in atomic-layered HfO<SUB>2</SUB> film grown on SiC substrate were examined as a function of the post-nitridation annealing temperature in an NH<SUB>3</SUB> ambient. As the post-nitridation annealing temperature increased up to 600°C, the incorporated nitrogen into the HfO<SUB>2</SUB>/SiC interface was gradually increased. The band gap and valence band offset were mostly increased as a function of the post-nitridation annealing temperature and the band alignment of HfO<SUB>2</SUB> films changed. O K-edge absorption features revealed two distinct band edge states below the conduction band edge in HfO<SUB>2</SUB> films, and these defect states were dramatically reduced with increasing of the post-nitridation annealing temperature. The reduction of defect states in HfO<SUB>2</SUB>/SiC improved the electrical properties such as the leakage current density, breakdown voltage, and trap charge density in the HfO<SUB>2</SUB> film and interface of HfO<SUB>2</SUB>/SiC.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Defect states in HfO<SUB>2</SUB>/SiC were studied as a function of the post nitridation temperature. </LI> <LI> Band edge states below the conduction band dramatically reduced. </LI> <LI> Changes of band edge states were related with the improvement of electrical properties. </LI> </UL> </P>

Variation of the nanostructural feature of nc-SiC:H thin films with post-deposition thermal annealing

Sen, C.D.,Son, J.I.,Kim, H.H.,Yun, H.S.,Cho, N.H. Elsevier Sequoia 2014 THIN SOLID FILMS - Vol.571 No.1

Amorphous silicon carbide (a-SiC) thin films were prepared by plasma enhanced chemical vapor deposition. The films were post-deposition annealed in a N<SUB>2</SUB>-H<SUB>2</SUB> atmosphere at temperatures ranging from 700 to 1300<SUP>o</SUP>C. As the annealing temperature was increased from 1000 to 1300<SUP>o</SUP>C, nanocrystalline silicon carbide (nc-SiC) formed and the mean crystallite size varied from~2 to~5nm. The thermal energy at high annealing temperatures broke the Si-H and C-H bonds, and rearranged the amorphous network to generate local crystalline states, resulting in the formation of nc-SiC. The photoluminescence (PL) peaks varied in the wavelength range of~425 to~470nm with annealing temperature. The optical band gap of the films has been associated to the maximum PL peak position and estimated to range from~2.92 to~2.64eV.

Transformation of charge polarity at HfO2/GaN interfaces through post-deposition annealing

Han Yoolim,Go Ju Mi,Yang Kyungmi,Kim Minsu,Kim Kwangeun 한국물리학회 2024 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.84 No.5

The transformation of charge polarity at HfO2/GaN interfaces was investigated through the post-deposition annealing (PDA) at 500 °C, 700 °C and 900 °C for 3 min. The change in surface property of atomic-layer deposition HfO2/GaN with the PDA conditions was estimated by a contact angle measurement. The PDA improved surface adhesion and thus decreased the contact angle of HfO2, which was shown with the PDA up to 700 °C. The increased contact angle with the PDA at 900 °C was presumably due to the transformation of crystallinity of HfO2 flm from amorphous to polycrystalline. The charge polarity at the HfO2/GaN interfaces was changed from negative to positive with the elevated PDA temperature. The energy band bending at the HfO2/GaN interfaces was described based on the elemental binding energy obtained by X-ray photoelectron spectroscopy. The charge polarity at the HfO2/GaN interface was converted at the 700 °C PDA with increased net charge density. The PDA afected the interface property of HfO2/GaN and determined the interface polarity and charge density.