Basic knowledge about the factors and mechanisms affecting the performance of solar cells and their identification is essential when thinking of future improvements to the device. Within this paper, we investigated the current transport mechanism in GaAsN p-i-n solar cells grown with atmospheric pressure metal organic vapour phase epitaxy (AP-MOVPE). We examined the electro-optical and structural properties of a GaAsN solar cell epitaxial structure and correlated the results with temperature-dependent current-voltage measurements and deep level transient spectroscopy findings. The analysis of J-V-T measurements carried out in a wide temperature range allows for the determination of the dominant current transport mechanism in a GaAsN-based solar cell device and assign it a nitrogen interstitial defect, the presence of which was confirmed by DLTFS investigation.

This paper proposes a novel method of average channel temperature and channel temperature profile determination is discussed in theoretical part and subsequently applied to InAlN/AlN/GaN HEMT using quasi-static I–V characterization supported by thermal 3D FEM simulations. Experimentally was determined HEMT source resistance and threshold voltage from low-power output and transfer I–V characteristics at different thermal chuck temperatures. The HEMT channel average temperature nearly 88 °C for dissipated power 2 W was calculated taking advantage of the drain current change analysis applied in recurrent differential form. Additionally, the HEMT channel temperature profile was simulated utilizing the calculated channel dissipated power density.

Trapping effects on two AlGaN/GaN Schottky diodes with a different composition of the AlGaN barrier layer were analyzed by current transient spectroscopy. The current transients were measured at a constant bias and at six different temperatures between 25 and 150 °C. Obtained data were fitted by only three superimposed exponentials, and good agreement between the experimental and fitted data was achieved. The activation energy of dominant traps in the investigated structures was found to be within 0.77–0.83 eV. This nearly identical activation energy was obtained from current transients measured at a reverse bias of −6 V as well as at a forward bias of+1 V. It indicates that the dominant traps might be attributed to defects mainly associated with dislocations connected predominantly with the GaN buffer near the AlGaN/GaN interface.

Electrical properties of recessed and non-recessed AlGaN/GaN Schottky diodes under off-state stress were investigated. The samples were consecutively stressed by the stepped negative bias (−60 V). Before and after the stress I−V and C−V characteristics were evaluated to verify the device degradation process. Finally, the degradation mechanism and the influence of AlGaN recessed layer thickness on the electrical properties of the Schottky diodes were analysed. It was found that the short time stress influence on I−V characteristics was most negligible for the non-recessed sample. Shallow and deep recessed samples exhibited initial trap filling and reverse current decrease. Generally it was found that the stress voltage near 60 V caused recoverable device degradation

We propose a novel model approach for temperature evaluation in the channel region of a InAlN/AlN/gallium nitride high electron mobility transistor (HEMT) due to self-heating effects. The heat transfer in a HEMT device has been investigated experimentally by the nearby temperature sensor and compared by theoretical models solved by both numerical and analytical methods. The average temperature of the channel area of almost 160 °C for dissipated power of 2 W was determined using the drain-source current variation analysis. The electrical and thermal behavioral numerical model under quasi-static conditions have been used to describe the HEMT device. In contrast, the one-dimensional thermal model for analytical evaluation has been proposed as an alternative approach. Surprisingly, the experimental results verified not only the validity of precise numerical simulation but also the simplified analytical model that makes it a reliable tool even for complex electronic devices.

An improved method of average channel temperature and channel temperature profile determination is introduced in this paper applied to AlGaN/GaN HEMT using quasi-static I – V characterization and external heater. Particular HEMT resistances and threshold voltage were experimentally determined at different ambient temperatures from TLM measurements, HEMT output and transfer I – V characteristics. Negligible pinch-off area and leakage current dependence on drain voltage allows to obtain average temperature ∼77 °C for dissipated power 1.5 W using simple recurrent differential calculations. The HEMT channel temperature profile exhibiting maximum peripheral temperature ∼130 °C for dissipated power 1.5 W was simulated and verified utilizing the device electrical parameters variation.