Investigation of Homojunction and Heterojunction Camel-Like Gate Field-Effect Transistors

• Main Authors: You-Ren, Wu, 吳友仁
• Other Authors: 蔡榮輝
• Format: Others
• Language: zh-TW
• Published: 2013
• Online Access: http://ndltd.ncl.edu.tw/handle/44476681222414885556

碩士 === 國立高雄師範大學 === 電子工程學系 === 101 === Investigation of Homojunction and Heterojunction Camel-Like Gate Field-Effect Transistors You-Ren Wu* Jung-Hui Tsai** Department of Electronics, National Kaohsiung Normal University, Kaohsiung, Taiwan, R.O.C Abstract In this thesis, we will use the development of simulation software to studied homojunction structure camel-like gate field-effect transistors and heterojunction structure camel-like gate field-effect transistors, in order to obtain better DC and high frequency characteristics,etc. First, the Silvaco software is employed to simulate the characteristics of the GaAs homojunction camel-gate field-effect transistors (device A) without the gate-to-source and gate-to-drain recess, and to compare the same transistor (device B) with recessed structure between gate-to-drain and gate-to-source region. The device A appears a second channel within the n+-GaAs cap layer resulting from the parallel conduction. Thus, a two-stage current and transconductance versus gate voltage are observed. Simulated results exhibit the characteristics of the device A (device B) with a gate barrier height up to 1.14 eV (1.14 eV), the transconductance of 525 mS/mm (148 mS/mm), a maximum saturation output current density approximates 447 mA/mm (351 mA/mm), a turn-on voltage up to 0.97 V (1.525 V), a unity current gain cut-off frequency of 9.6 GHz (9.1 GHz), and a maximum oscillation frequency are 13.7 GHz (13.5 GHz), respectively. In chapter 2, we studied the influence of channel concentration on GaAs homojunction camel-like gate n-channel field-effect transistors. Two devices have not recess structures and the channel concentration is changed from n = 1  1018 cm-3 (device A) to 1  1017 cm-3 (device C). For the device C, the results exhibit the gate barrier height only 0.65 eV, the transconductance of 137 mS/mm, the maximum saturation output current density of 29.5 mA/mm, the turn-on voltage of 0.965 V, the unity current gain cut-off frequency of 7.4 GHz, and maximum oscillation frequency of 11.6 GHz, respectively. III-V heterojunction field-effect transistors in digital and microwave circuit applications provide a promise of potential development. In chapter 4, we will focuse on the InGaP/GaAs or AlGaAs/GaAs camel-like gate heterojunction field-effect transistors, which has a large energy-gap InGaP or AlGaAs layer to endure a maximum electric field for endurancing gate breakdown voltage. In addition, the conduction band discontinuity (△Ec) at heterojunction with good confinement effect for electrons in channel can achieve a larger gate turn-on voltage, drain -source current, and transconductance. According to the simulation results, the device D (InGaP/GaAs camel-gate FET) and device E (AlGaAs/GaAs camel-gate FET) show barrier heights up to 1.13 eV and 1.28 eV, maximum transconductances of 477 mS/mm and 476.8 mS/mm, maximum saturation output current densities of 207.8 mA/mm and 207.8 mA/mm, gate turn-on voltages up to 0.96 V and 0.97 V, unity current gain cut-off frequencies of 6.13 GHz and 6.1GHz, and maximum oscillation frequencies of 10.5 GHz and 8.95 GHz, respectively. * Author ** Advisor KEYWORDS: parallel conduction, InGaP/GaAs, AlGaAs/GaAs