Activation Energy of RTS Noise

Low frequency noise was measured in silicon MOSFET and GaN and InGaAs based HFET devices with special emphasis on the RTS noise. The RTS (Random Telegraph Signal) dependence on the biasing conditions and temperature was analyzed in order to obtain new information regarding production technology. From the time dependence of the RTS noise voltage the mean time of charge carriers capture and emission by traps in the gate oxide layer was determined as a function of applied gate and drain voltage or electron concentration and then several important trap parameters, such as activation energy and position in the channel could be estimated

Low Frequency Noise of Tantalum Capacitors

A low frequency noise and charge carriers transport mechanism analysis was performed on tantalum capacitors in order to characterise their quality and reliability. The model of Ta−Ta2O5−MnO2 MIS structure was used to give physical interpretation of VA characteristic both in normal and reverse modes. The self-healing process based on the high temperature MnO2−Mn2O3 transformation was studied and its kinetic determined on the basis of noise spectral density changes. The correlation between leakage current and noise spectral density was evaluated and noise reliability indicator was suggested. In normal mode the noise spectral density at rated voltage increases with second power of current and it varies within two decades for given leakage current value. In reverse mode there is only weak correlation and for given applied voltage, the leakage current for all ensemble varies only by one order, whereas the noise spectral density of the same samples spread in five orders

Nature of low-energy optical emission in doped AlGaN/GaN heterostructures

Photoluminescence (PL) in modulation-doped and nominally undoped AlxGa1-xN/GaN heterostructures was studied and compared with PL spectra of GaN films grown on sapphire substrates. It is demonstrated that optical emission in the energy range of 3.3-3.46 eV related to the two-dimensional electron gas radiative processes can be completely suppressed in modulation-doped AlxGa1-xN/GaN heterostructures. Instead of this, an intense broad long-wavelength emission attributed to the recombination of donor-acceptor pairs in the lower energy range of 2.7-3.3 eV is revealed. This spectral transformation is explained by the presence of deep-level defect-related acceptor centers in AlxGa1-xN/GaN heterostructures introduced at the modulation doping of the AlxGa1-xN barrier layer. (c) 2007 American Institute of Physics