Fig. 4: Device characteristics of the HEMTs and LEDs, operating independently.
From: Using both faces of polar semiconductor wafers for functional devices
a, Normalized drain current (black line) and transconductance (grey line) of an N-polar HEMT as a function of gate-source voltage, operating at a drain-source voltage of 5 V. b, Linear plot showing the family of curves for a HEMT (black lines) for a gate-source voltage ranging from 1.75 (on) to −3.25 V (off). On the right axis, the linear current–voltage characteristics of a 400-μm-diameter LED (blue line) and unnormalized output characteristics of a HEMT are shown as well. The dimensions of the measured HEMTs are LSD = 4 μm, LG = 1.5 μm and WG = 50 μm. c, Semi-log plots showing the unnormalized drain current (solid black line) and gate current (dashed black line) versus gate-source voltage, for a drain-source voltage of 5 V. Here the transistor current corresponds to the left vertical axis. The horizontal dashed black line indicates a normalized channel sheet current density of 1 A mm−1. Similarly, corresponding to the right vertical axis is the LED current (blue line) as a function of forward bias for a 400-μm-diameter device. d, Electroluminescence spectra of a metal-polar, 400-μm-diameter LED. The injection current density ranges from 1 to 140 A cm−2. The inset shows a camera image of the sample with an LED in the on state. a.u., arbitrary units.
