Study of Surfactant-Like Sb in Heterojunction Field Effect Transistor

• Main Authors: Po-Jung Hu, 胡栢榕
• Other Authors: W. C. Hsu
• Format: Others
• Language: en_US
• Published: 2007
• Online Access: http://ndltd.ncl.edu.tw/handle/96726245092457007931

碩士 === 國立成功大學 === 微電子工程研究所碩博士班 === 95 === We suggest two ways to improve thermal stability in this study. First, a high electron-mobility transistor (HEMT) by using a dilute antimony InGaAsN(Sb) channel has been successfully investigated. The advantages by incorporating the surfactant-like Sb atoms during growth of InGaAsN/GaAs quantum well (QW) consist of the suppression of the three-dimensional growth and the improved crystalline quality. The experimental results of the studied device by using a dilute antimony InGaAsN(Sb) channel can improve the channel layer quality and enhance carrier confinement. Thus, compared with InGaAsN HEMT, InGaAsN(Sb) HEMT has better dc characteristics and highly thermal stability. The values of the gm, max and the drain-source current density (IDSS), are 109 (66.4) mS/mm and 87 (70) mA/mm at room temperature for the studied HEMT with (without) adding the Sb atoms into the InGaAsN channel, respectively. Significant improvement in gm and IDSS values has been successfully achieved by employing the dilute antimony channel. The thermal threshold coefficient (Vth/T) is -0.807 (-1.07) mV/K for the InGaAsN(Sb) HEMT and the conventional InGaAsN HEMT at 300 (450)K, respectively. Second, we apply doped channel structure to the InGaAs(Sb) HEMT in order to future improve thermal stability. When temperature rises, the device performance is affected slightly by increasing carrier concentration in the channel. Thus, the degradation of device performance at high temperature is insignificant. Although the studied device can not improve the peak extrinsic transconductance and drain-to-source saturation current density due to mobility decreasing, the doped channel InGaAs(Sb) HFET demonstrates the great gate-voltage swing (GVS) value is 1.63 V compared with that is 1.2 V of InGaAs(Sb) HEMT. The better GVS characteristic of doped channel InGaAs(Sb) HFET is owing to the carriers have been uniformly distributed in the channel and the channel has been depleted slowly. Besides, the present doped channel device also achieves superior stable thermal characteristics. The thermal threshold coefficient (Vth/T) is -0.70 (-1.54) mV/K for the InGaAs(Sb) doped channel HFET and the InGaAs(Sb) HEMT at 300 (450)K, respectively.