In this study, we measured and comparatively analyzed the characteristics of MPS (Merged Pin Schottky) diodes in 4H-SiC by changing the areal ratio between the Schottky and PN junction region. Increasing the temperature from 298 K to 473 K resulted in the threshold voltage shifting from 0.8 V to 0.5 V. A wider Schottky region indicates a lower on-resistance and a faster turn-on. The effective barrier height was smaller for a wider Schottky region. Additionally, the depletion layer became smaller under the influence of the reduced effective barrier height. The wider Schottky region resulted in the ideality factor being reduced from 1.37 to 1.01, which is closer to an ideal device. The leakage saturation current increased with the widening Schottky region, resulting in a 1.38 times to 2.09 times larger leakage current.
1,200 V class junction barrier schottky (JBS) diodes and schottky barrier diodes (SBD) were simultaneously fabricated on the same 4H-SiC wafer. The resulting diodes were characterized at temperatures from room temperature to 473 K and subsequently compared in terms of their respective I-V characteristics. The parameters deduced from the observed I-V measurements, including ideality factor and series resistance, indicate that, as the temperature increases, the threshold voltage decreases whereas the ideality factor and barrier height increase. As JBS diodes have both Schottky and PN junction structures, the proper depletion layer thickness, Ron, and electron mobility values must be determined in order to produce diodes with an effective barrier height. The comparison results showed that the JBS diodes exhibit a larger effective barrier height compared to the SBDs.
Silicon carbide is widely used in power semiconductor devices owing to its high energy gap. In particular, Schottky barrier diode (SBD) and PiN diodes fabricated on 4H-SiC wafers are being applied to various fields such as power devices. The characteristics of SBD and PiN diodes can be extracted from C-V and I-V characteristics. The measured Schottky barrier height (SBH) was 1.23 eV in the temperature range of 298~473 K, and the average ideal factor is 1.17. The results show that the device with the Schottky contact is characterized by the theory of thermal emission. As the temperature increases, the parameters are changed and the Vth is shifted to lower voltages.
The temperature dependent characteristics on the properties of SiC Schottky Diode has beeninvestigated. In this study, the temperature dependent current-voltage characteristics of the SiC Schottkydiode were measured in the range of 300 ∼ 500 K. Divided into pre- and post- irradiated device wasmeasured. The barrier height after irradiation device at 500 K increased 0.15 eV compared to 300 K, thebarrier height of pre- neutron irradiated Schottky diode increased 0.07 eV. The effective barrier heightafter irradiation increased from 0.89 eV to 1.05 eV. And ideality factor of neutron irradiated Schottkydiode at 500 K decreased 0.428 compared to 300 K, the ideality factor of pre- neutron irradiated Schottkydiode decreased 0.354. Also, a slight positive shift in threshold voltage from 0.53 to 0.68 V. we analyzedthe effective barrier height and ideality factor of SiC Schottky diode as function of temperature.
The effect of neutron irradiation on the properties of SiC Schottky Diode has been investigated. SiC Schottky diodes were irradiated under neutron fluences and compared to the reference samples to study the radiation-induced changes in device properties. The condition of neutron irradiation was 3.1×1010n/cm2. The current density after irradiation decreased from 12.7 to 0.75 A/cm2. Also, a slight positive shift (ΔVth= 0.15 V) in threshold voltage from 0.53 to 0.68 V and a positive change (ΔΦB= 0.16 eV) of barrier height from 0.89 to 1.05 eV have been observed by the neutron irradiation, which is attributed to charge damage in the interface between the metal and the SiC layer.
We optimize electrical and optical properties of thermal and SF6 plasma treated indium tin oxide (ITO)/Al based reflector for high-power ultraviolet (UV) light-emitting diodes (LEDs). After thermal and SF6 plasma treatments of ITO/Al reflector, the specific contact resistance decreased from 1.04×10(-3) Ω·cm2 to 9.12×10(-4) Ω·cm2, while the reflectance increased from 58% to 70% at the 365 nm wavelength. The low resistance and high reflectance of ITO/Al reflector are attributed to the reduced Schottky barrier height (SBH) between the ITO and AlGaN by large electronegativity of fluorine species and reduced interface roughness between the ITO and Al, respectively.
We report on the formation mechanism of large Schottky barrier height (SBH) of nonalloyed Cr Schottky contacts on strained Al0.25Ga0.75N/GaN. Based on the current-voltage (I-V) and capacitance-voltage (C-V) data, the SBHs are determined to be 1.98 (±0.02) and 2.07 (±0.02) eV from the thermionic field emission and two-dimensional electron gas (2DEG) calculations, respectively. Possible formation mechanism of large SBH will be described in terms of the formation of Cr-O chemical bonding at the interface between Cr and AlGaN/GaN, low binding-energy shift to surface Fermi level, and the reduction of 2DEG electrons.
By improving the conducting process of metal source/drain (S/D) in direct contact with the channel, schottky barrier metal-oxide-semiconductor field effect transistors (SB MOSFETs) reveal low extrinsic parasitic resistances, offer easy processing and allow for well-defined device geometries down to the smallest dimensions. In this work, we investigated the arrhenius plots of the SB MOSFETs with different S/D schottky barrier (SB) heights between simulated and experimental current-voltage characteristics. We fabricated SB MOSFETs using difference S/D metals such as Cr (ФCr~4.5 eV) and Ni (ФNi~5.2 eV), respectively. Schottky barrier height (ФB) of the fabricated devices were measured to be 0.25~0.31 eV (Cr-S/D device) and 0.16~0.18 eV (Ni-S/D device), respectively in the temperature range of 300 K and 475 K. The experimental results have been compared with 2-dimensional simulations, which allowed bandgap diagram analysis.
Abstract: We have fabricated schottky barrier diode (SBDs) using polar (c-plane) and non polar (a-, m-plane) n-type 6H-SiC wafers. Ni/SiC ohmic contact was accomplished on the backside of the SiC wafers by thermal evaporation and annealed for 20minutes at 950℃ in mixture gas (N(2) 90% + H(2) balanced). The specific contact resistance was 3.6×10-4 Ω㎝2 after annealing at 950℃. The XRD results of the alloyed contact layer show that formation of NiSi2 layer might be responsible for the ohmic contact. The active rectifying electrode was formed by the same thermal evaporation of Ni thin film on topside of the SiC wafers and annealed for 5 minutes at 500℃ in mixture gas (N(2) 90% + H(2) balanced). The electrical properties of SBDs have been characterized by means of I-V and C-V curves. The forward voltage drop is about 0.95 V, 0.8 V and 0.8 V for c-, a- and m-plane SiC SBDs respectively. The ideality factor (η) of all SBDs have been calculated from log(I)-V plot. The values of ideality factor were 1.46, 1.46 and 1.61 for c-, a- and m-plane SiC SBDs, respectively. The schottky barrier height (SBH) of all SBDs have been calculated from C-V curve. The values of SBH were 1.37 eV, 1.09 eV and 1.02 eV for c-, a- and m-plane SiC SBDs, respectively.
Effects of Emission Layer Thickness on the Efficiency of Blue Phosphorescent Organic Light Emitting Diodes with Triple Layer Structure Yu Seok Seo, Dae Gyu Moon Journal of Korean Institute of Electrical and Electronic Materials Engineers.2010; 23(2): 143. CrossRef
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