Studies of InAlGaP/GaAs and InAlAsSb/InP Heterostructure Transistors

• Main Authors: Yu-Shyan Lin, 林育賢
• Other Authors: Wei-Chou Hsu
• Format: Others
• Language: en_US
• Published: 2000
• Online Access: http://ndltd.ncl.edu.tw/handle/75117055138396527448

博士 === 國立成功大學 === 電機工程學系 === 88 === In this thesis, the properties of In0.5(AlXGa1-X)0.5P/GaAs and In0.34Al0.66As0.85Sb0.15/InP and their important contributions to the field of electronic devices have been proposed, including single and double heterostructure-emitter bipolar transistors (SHEBT''s and DHEBT''s) and heterostructure field-effect transistors (HFET''s). Improved InGaP/GaAs HEBT''s by inserting undoped GaAs spacer layers at both sides of the base have been demonstrated. The unpassivated SHEBT and DHEBT with 100 A spacer exhibit common-emitter current gains of 200 and 120 along with offset voltage of 80 and 50 mV, respectively. The current gains of the passivated SHEBT and DHEBT are increased to 360 and 180, respectively. In addition, the passivated SHEBT exhibits a current gain over unity at ultralow current densities of 10-5 A/cm2. A symmetric double d-doped In0.5Ga0.5P/In0.25Ga0.75As/GaAs high electron mobility transistor (HEMT) has been fabricated. Improved two-dimension electron gas (2DEG) density and mobility at 300 (77) K as high as 3.85 (3.8) x 1012 cm-2 and 5410 (19200) cm2/V·S are achieved, respectively. The maximum gate-source breakdown voltage was up to 75 V. The high breakdown voltage, to our knowledge, is among the best in the GaAs-based HFET''s. We have proposed the first In0.5(Al0.66Ga0.34)0.5P/GaAs heterostructure field- effect transistor grown on semi-insulsting GaAs substrate {2o off (100) towards [111]}. Misorientated GaAs substrate was used to reduce the long range ordering. The extrinsic transconductance was as high as 170 mS/mm with a gate geometry of 1.5 x 125 mm2. An extremely low gate reverse leakage current of 0.069 mA/mm at Vgs = - 40 V is achieved. In addition, the device can be operated up to 410 mA/mm at VGS = 1.5 V before saturation. A novel InP-based HFET using undoped In0.34Al0.66As0.85Sb0.15 as Schottky layer and coupled d-doped InP as the channel has been demonstrated. According to the transitivity rule, we have predicted that the InAlAsSb/InP shows the type II heterostructure and has a large DEC of 0.7 eV at the InAlAsSb/InP heterojunction. By virtue of the coupled d-doped structure, a 2DEG concentration (n2DEG) of 3.3 x 1012 cm-2 along with mobility (mn) of 2761 cm2/V·S is achieved. An extremely low gate reverse leakage current of 111 mA/mm at Vgs = - 40 V is achieved. The three-terminal on- and off-state breakdown voltages are as high as 40.8 V and 16.1 V, respectively. The output conductance is as low as 1.8 mS/mm even when the drain-to-source voltage is 15 V.