Optical and electrical characterization of the AlGaAs/GaAs/InGaAs pseudomorphic high electron mobility transistor structures

• Main Authors: Chang, Han-Yu, 張翰宇
• Other Authors: Lin, Der-Yuh
• Format: Others
• Language: zh-TW
• Published: 2017
• Online Access: http://ndltd.ncl.edu.tw/handle/9g6m39

碩士 === 國立彰化師範大學 === 電子工程學系 === 106 === We will present the studies of two-dimensional electron gas (2DEG) in four AlGaAs/GaAs/InGaAs pseudomorphic high electron mobility transistor structures with different thickness of schottky layer and different doping concentration in planar-doping layer using current-voltage (I-V), photoluminescence (PL), photocurrent (PC), photovoltage (PV), Hall effect measurement in the temperature range between 20 and 340 K. The samples used in this study were grown on GaAs substrate by metal organic chemical vapor deposition (MOCVD) method. In the PL spectra, the optical features are identified to be the transitions coming from InGaAs channel layer. In low temperature PL spectra of samples A, B, C and D, the second luminescence feature reveals quite weak, because the Fermi level is lower than the second electron subband. In addition, as temperature decreases, the signal exhibits blue shift phenomenon. As the low temperature makes the lattice constant shrinkage, resulting in the transitions band gap becomes larger. For the PC measurement, the gandgap of GaAs and AlGaAs layer and the intersubband transitions in the InGaAs channel layer are deduced. To understand the two dimensional electron gas (2DEG), temperature-dependent and pressure dependent Hall measurement were carried. From the pressure dependent Hall measurement, both mobility and resistivity of the sample are very sensitive to pressure variety due to ion adsorption effect on the sample surface, indicating doping concentration in planar-doping layer of pHEMTs is critical for pressure sensor application.