An enhanced small-signal model is introduced to model the influence of the impact ionization effect on the performance of In As/Al Sb HFET, in which an optimized fitting function D（ωτi） in the form of least square...An enhanced small-signal model is introduced to model the influence of the impact ionization effect on the performance of In As/Al Sb HFET, in which an optimized fitting function D（ωτi） in the form of least square approximation is proposed in order to further enhance the accuracy in modeling the frequency dependency of the impact ionization effect.The enhanced model with D（ωτi） can accurately characterize the key S parameters of In As/Al Sb HFET in a wide frequency range with a very low error function EF. It is demonstrated that the new fitting function D（ωτi） is helpful in further improving the modeling accuracy degree.展开更多
HfAlO/InAlAs metal-oxide-semiconductor capacitor (MOS capacitor) is considered as the most popular candidate of the isolated gate of InAs/AlSb high electron mobility transistor (HEMT). In order to improve the performa...HfAlO/InAlAs metal-oxide-semiconductor capacitor (MOS capacitor) is considered as the most popular candidate of the isolated gate of InAs/AlSb high electron mobility transistor (HEMT). In order to improve the performance of the HfAlO/InAlAs MOS-capacitor, samples are annealed at different temperatures for investigating the HfAlO/InAlAs interfacial characyeristics and the device's electrical characteristics. We find that as annealing temperature increases from 280 ℃ to 480 ℃, the surface roughness on the oxide layer is improved. A maximum equivalent dielectric constant of 8.47, a minimum equivalent oxide thickness of 5.53 nm, and a small threshold voltage of -1.05 V are detected when being annealed at 380 ℃;furthermore, a low interfacial state density is yielded at 380 ℃, and this can effectively reduce the device leakage current density to a significantly low value of 1×10-7 A/cm2 at 3-V bias voltage. Therefore, we hold that 380 ℃ is the best compromised annealing temperature to ensure that the device performance is improved effectively. This study provides a reliable conceptual basis for preparing and applying HfAlO/InAlAs MOS-capacitor as the isolated gate on InAs/AlSb HEMT devices.展开更多
AHfO2/n–In Al As MOS-capacitor has the advantage of reducing the serious gate leakage current when it is adopted in In As/Al Sb HEMT instead of the conventional Schottky-gate. In this paper, three kinds of Hf O2/n–I...AHfO2/n–In Al As MOS-capacitor has the advantage of reducing the serious gate leakage current when it is adopted in In As/Al Sb HEMT instead of the conventional Schottky-gate. In this paper, three kinds of Hf O2/n–InAlAs MOS-capacitor samples with different Hf O2 thickness values of 6, 8, and 10 nm are fabricated and used to investigate the interfacial and electrical characteristics. As the thickness is increased, the equivalent dielectric constant ε ox of Hf O2 layer is enhanced and the In AlAsHfO2 interface trap density Ditis reduced, leading to an effective reduction of the leakage current. It is found that the Hf O2 thickness of 10 nm is a suitable value to satisfy the demands of most applications of a HfO2/n–InAlAs MOS-capacitor, with a sufficiently low leakage current compromised with the threshold voltage.展开更多
文摘An enhanced small-signal model is introduced to model the influence of the impact ionization effect on the performance of In As/Al Sb HFET, in which an optimized fitting function D（ωτi） in the form of least square approximation is proposed in order to further enhance the accuracy in modeling the frequency dependency of the impact ionization effect.The enhanced model with D（ωτi） can accurately characterize the key S parameters of In As/Al Sb HFET in a wide frequency range with a very low error function EF. It is demonstrated that the new fitting function D（ωτi） is helpful in further improving the modeling accuracy degree.
文摘HfAlO/InAlAs metal-oxide-semiconductor capacitor (MOS capacitor) is considered as the most popular candidate of the isolated gate of InAs/AlSb high electron mobility transistor (HEMT). In order to improve the performance of the HfAlO/InAlAs MOS-capacitor, samples are annealed at different temperatures for investigating the HfAlO/InAlAs interfacial characyeristics and the device's electrical characteristics. We find that as annealing temperature increases from 280 ℃ to 480 ℃, the surface roughness on the oxide layer is improved. A maximum equivalent dielectric constant of 8.47, a minimum equivalent oxide thickness of 5.53 nm, and a small threshold voltage of -1.05 V are detected when being annealed at 380 ℃;furthermore, a low interfacial state density is yielded at 380 ℃, and this can effectively reduce the device leakage current density to a significantly low value of 1×10-7 A/cm2 at 3-V bias voltage. Therefore, we hold that 380 ℃ is the best compromised annealing temperature to ensure that the device performance is improved effectively. This study provides a reliable conceptual basis for preparing and applying HfAlO/InAlAs MOS-capacitor as the isolated gate on InAs/AlSb HEMT devices.
基金Project supported by the National Basic Research Program of China(Grant No.2010CB327505)the Advance Research Foundation of China(Grant No.914xxx803-051xxx111)
文摘AHfO2/n–In Al As MOS-capacitor has the advantage of reducing the serious gate leakage current when it is adopted in In As/Al Sb HEMT instead of the conventional Schottky-gate. In this paper, three kinds of Hf O2/n–InAlAs MOS-capacitor samples with different Hf O2 thickness values of 6, 8, and 10 nm are fabricated and used to investigate the interfacial and electrical characteristics. As the thickness is increased, the equivalent dielectric constant ε ox of Hf O2 layer is enhanced and the In AlAsHfO2 interface trap density Ditis reduced, leading to an effective reduction of the leakage current. It is found that the Hf O2 thickness of 10 nm is a suitable value to satisfy the demands of most applications of a HfO2/n–InAlAs MOS-capacitor, with a sufficiently low leakage current compromised with the threshold voltage.
