Gallium Nitride Electrical Characteristics Extraction and Uniformity Sorting

Abstract

This study examined the output electrical characteristics—current-voltage (I-V) output, threshold voltage, and parasitic capacitance—of novel gallium nitride (GaN) power transistors. Experimental measurements revealed that both enhanced- and depletion-mode GaN field-effect transistors (FETs) containing different components of identical specifications yielded varied turn-off impedance; hence, the FET quality was inconsistent. Establishing standardized electrical measurements can provide necessary information for designers, and measuring transistor electrical characteristics establishes its equivalent-circuit model for circuit simulations. Moreover, high power output requires multiple parallel power transistors, and sorting the difference between similar electrical characteristics is critical in a power system. An isolated gate driver detection method is proposed for sorting the uniformity from the option of the turn-off characteristic. In addition, an equivalent-circuit model for GaN FETs is established on the basis of the measured electrical characteristics and verified experimentally.

Simulation Model Development for Packaged Cascode Gallium Nitride Field-Effect Transistors

“…Results from other studies [11] have revealed that the lower the V S(off) values are, the closer the parasitic capacitances are to those specified on the datasheet, with the devices with the lowest V S(off) being used as test transistors. Here, the off-state voltage V s(off) of the fabricated cascode GaN FET was 20 V, and the leakage current obtained using the curve tracer and the calculated leakage current were extremely close (20 V/3.64 MΩ = 5.5 µA).…”

“…Figure 12 shows the results of the analysis of the leakage current that was obtained using the curve tracer. The plot of VDS versus IDSS reveals that the leakage current hold was 2.2 μA when the drain-to-source voltage was higher than 22 V. This leakage current result was approximated from uniformity sorting methods developed elsewhere [11]. VS(off) was measured after applying different drain-to-source voltages between 10 and 180 V (red circles in Figure 11).…”

“…Results from other studies [11] have revealed that the lower the VS(off) values are, the closer the parasitic capacitances are to those specified on the datasheet, with the devices with the lowest VS(off) being used as test transistors. Here, the off-state voltage Vs(off) of the fabricated cascode GaN FET was 20 V, and the leakage current obtained using the curve tracer and the calculated leakage current were According to a previous study [11] on uniformity sorting methods, device uniformity can be indirectly screened by utilizing turn-off resistance with an isolated gate drive detection circuit. A 10 × (10 MΩ) probe was employed for the measurement (R L = 10 MΩ).…”

“…From the static characteristic, the plateau voltage (VPL) in the gate charge curve is read from the transfer characteristic graph with the test current, whereas the individual gate charge is derived from the parasitic capacitance curves. Gate charge information predicts switching behavior, and turnoff resistance and leakage current are estimated using the sorting method [11].…”

“…Future research should explore these concepts in the model to discover more precise characteristics about GaN FETs for practical applications. According to a previous study [11] on uniformity sorting methods, device uniformity can be indirectly screened by utilizing turn-off resistance with an isolated gate drive detection circuit. A 10 × (10 MΩ) probe was employed for the measurement (RL = 10 MΩ).…”