Malek Gassoumi

Electrical characterization of (Ni/Au)/Al0.25Ga0.75N/GaN/SiC Schottky barrier diode

In this work we report on the characteristics of a (Ni/Au)/AlGaN/GaN/SiC Schottky barrier diode (SBD). A variety of electrical techniques, such as gate current-voltage (I-V), capacitance-voltage (C-V), and deep level transient spectroscopy (DLTS) measurements have been used to characterize the diode. The behavior study of the series resistance, RS, the ideality factor, n, the effective barrier height, Φb, and the leakage current with the temperature have emphasized an inhomogeneity of the barrier height and a tunneling mechanism assisted by traps in the SBD. Hence, C-V measurements successively sweeping up and down the voltage have demonstrate a hysteresis phenomenon which is more pronounced in the temperature range of 240 to 320 K, with a maximum at ∼300 K. This parasitic effect can be attributed to the presence of traps activated at the same range of temperature in the SBD. Using the DLTS technique, we have detected one hole trap having an activation energy and a capture cross-section of 0.75 eV and 1.0...

Self-heating and trapping effects in AlGaN/GaN heterojunction field-effect transistors

This work first attempted to simulate the band edges of AlGaN/GaN high electron mobility transistors (HEMTs) structures with Ga-face polarity at the heterointerface. The spontaneous and piezoelectric-induced polarization fields as well as the effects of temperature on the electron band parameters have been included into the modeling. In a second step, we calculated self-consistently direct-current characteristics of AlGaN/GaN HEMTs without considering any defect. Calculations were made as a function of doping concentration and Al composition. In the paper, the self-heating in AlGaN/GaN HEMTs grown on SiC substrate before and after Si3N4 passivation was also investigated revealing that: (i) power dissipation is induced due to the increase in drain bias, which leads to a temperature rise of the two-dimensional electron gas in the channel, (ii) an enhancement in drain current is achieved after Si3N4 passivation, (iii) the self-heating occurs even in AlGaN/GaN heterostructures after passivation. Including the...

Anomaly and defects characterization by I-V and current deep level transient spectroscopy of Al0.25Ga0.75N/GaN/SiC high electron-mobility transistors

In this paper, we report static electric drain-source current-voltage measurements for different gate voltages and at different temperatures, performed on Al0.25Ga0.75N/GaN/SiC high electron-mobility transistors (HEMT). The results show the presence of kink and collapse effects. We have demonstrated that these effects are significant in the temperature range varying from 150 to 400 K with a maximum around 300 K. This parasitic effect was correlated with the presence of deep levels in our transistor. Indeed, we have noticed the presence of two electron traps named A1 and A2, and one hole trap named H1; their respective activation energies, which are determined using current deep level transient spectroscopy (CDLTS), are, respectively, 0.56, 0.82, and 0.75 eV. Traps H1 and A1 are shown to be extended defects in the Al0.25Ga0.75N/GaN heterostructure; they are supposed to be the origin of the kink and collapse effects. However, the punctual defect A2 seems to be located either in the free gate-drain surface, ...

Effect of surface passivation by SiN/SiO2 of AlGaN/GaN high-electron mobility transistors on Si substrate by deep level transient spectroscopy method

Device performance and defects in AlGaN/GaN high-electron mobility transistors have been correlated. The effect of SiN/SiO2 passivation of the surface of AlGaN/GaN high-electron mobility transistors on Si substrates is reported on DC characteristics. Deep level transient spectroscopy (DLTS) measurements were performed on the device after the passivation by a (50/100 nm) SiN/SiO2 film. The DLTS spectra from these measurements showed the existence of the same electron trap on the surface of the device.

High Frequency Analysis and Small-Signal Modeling of AlGaN/GaN HEMTs with SiO2/SiN Passivation

AlGaN/GaN high electron mobility transistors (HEMTs) on Silicon substrates grown by molecular beam epitaxy have been investigated using small-signal microwave measurements, to see performance Radio-frequency of components. Passivation of HEMT devices SiO2/SiN a different pretreatment is used to reduce the effects of trapping and consequently has a large effect on these radio-frequency parameters. We used cold-FET and hot FET technique to extract the intrinsic and extrinsic parameters in order to show the effect passivation of parasitic elements; the parasitic capacitances, resistances and inductances. From this point we discover the extent of their impact on power and microwave performance.

Electron/transport in (Mo/Au)/AlGaN/GaN Schottky diode

The knowledge of the conduction mechanisms in a Schottky barrier is essential to calculate the Schottky barrier parameters and to explain the observed effects. In the present work, we report temperature- dependent current-voltage characteristics of (Mo/Au)/Al0.26Ga0.74N/GaN/Si/ Schottky barrier diodes. Measurements were performed in the temperature range of 80 -300 K.Results have been explained based on the thermionic emission mechanism with lateral inhomogeneity at the (Mo/Au/AlGaN/GaN/Si) interface. As is shown, the barrier height ΦB0 as well as the ideality factor n exhibit an important temperature dependence and the anomaly resulting from this dependence has been explained by invoking two sets of Gaussian distributions at the metal/semiconductor interface for temperature ranging from 80 K to 160 K and from 160K to300 K, respectively. It is also found that the values of Rs obtained from Cheungs method strongly depend on temperature and decrease with decreasing temperature. Keywords: Schottky barrier, Current-voltage characteristics, Ideality factor, Inhomogeneity, Thermionic emission.

Conductance Deep-Level Transient Spectroscopic Study of 4H- SiC MESFET and Traps

Silicon carbide (SiC) is an important material for fabricating high-power, high-temperature and high frequency devices [1]. The semi-insulating (SI) form of 4H-SiC is useful for making microwave devices [2] because it helps in lowering the stray device capacitances, thereby in‐ creasing the maximum operating frequency of the device. Selective area ion implantation is regarded as an attractive doping method for fabricating MESFETs in bulk SI 4H-SiC [3–5] due to the ease of inter-device isolation without the loss of planarity.