Low-frequency noise in heterojunction FETs with low-temperature buffer

Low-frequency noise was measured on heterojunction FETs grown on low-temperature buffer and superlattice buffer layers. A distinct generation-recombination noise source with an activation energy of 0.70 eV was observed in devices built on a low-temperature buffer. Both structures showed a trap with an activation energy ( approximately 0.50 eV) that has a gate-to-source voltage dependence and is believed to be due to interactions between electrons in the channel and traps in the AlGaAs supply layer. Computer simulations of the position of the energy levels as a function of the gate voltage support this idea. A trap due to DX centers with an activation energy of approximately 0.30 eV in AlGaAs was also observed in both devices.< >