Electrical Transport

DC resistance/conductivity by direct probe

GTUB3 single crystals and small crystal bundles under DC probe · Single Crystal

Keithley DMM4050 6.5-digit multimeter; stainless-steel probe moved by x/y/z micrometer stages under optical microscope; about 200 random measurements; two-wire/probe resistance about 8 Ohm compensated.

Geometry: stainless-steel probe to crystals on copper electrode
Context: pristine GTUB3
Measurement source: S14-S15 · 7. DC Measurements of Electrical Conductivity

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
average DC electrical conductivityMarked as a best value within this paper	4 S m-1	—	—	Calculated From Reported Approximate	5 · 2.4 Electrical Conductivity Measurements
DC electrical conductivity range maximum	8 S m-1	—	—	Calculated From Reported Range	5 · 2.4 Electrical Conductivity Measurements
DC electrical conductivity range minimum	2 S m-1	—	—	Calculated From Reported Range	5 · 2.4 Electrical Conductivity Measurements
two-wire/probe baseline resistance	~8 Ohm	—	—	Text Approximate	S15 · 7. DC Measurements
DC resistance range maximum	300 Ohm	—	—	Text Range	5 · 2.4 Electrical Conductivity Measurements
DC resistance range minimum	100 Ohm	—	—	Text Range	5 · 2.4 Electrical Conductivity Measurements

impedance spectroscopy with variable electrode spacing

Impedance spectroscopy

GTUB3 crystal ensemble in parallel-electrode impedance jig · Single Crystal

Digilent Analog Discovery 2 with impedance analyser; 1 kOhm reference resistor; 5 V excitation; 100 Hz-1 MHz; 10 measurements averaged at each frequency; gap 19.40-19.60 mm in 0.01 mm steps.

Geometry: parallel two-electrode micrometer jig, copper discs 12.7 mm diameter and 6.35 mm height
Context: pristine GTUB3
Measurement source: S8-S14 · 6. Impedance Measurements of Electrical Conductivity · Figures S7-S10

Property	Reported value	Normalised value	Uncertainty	Origin and quality	Source
blank-system parallel capacitance fit	C_0 = 7.6961 +/- 0.0328 pF	—	+/- 0.0328 pF	Visual Estimate Approximate	S12 · Figure S8 annotation · Figure S8
blank-system offset distance fit	d_0 = 19.481 +/- 7.36e-04 mm	—	+/- 7.36e-04 mm	Visual Estimate Approximate	S12 · Figure S8 annotation · Figure S8
large-gap capacitance typical maximum	20 pF	—	—	Text Range	S10 · 6. Impedance Measurements · Figure S7
large-gap capacitance typical minimum	10 pF	—	—	Text Range	S10 · 6. Impedance Measurements · Figure S7
first conduction observed	19.52 mm	—	—	Text Approximate	S12 · 6. Impedance Measurements · Figure S8
impedance-derived electrical conductivityMarked as a best value within this paper	0.03 S m-1	—	—	Calculated From Reported Approximate	5 · 2.4 Electrical Conductivity Measurements · Figure 3C; Figure S9
contact surface area for impedance calculation	A = 13 mm2	—	—	Text Approximate	5 · 2.4 Electrical Conductivity Measurements
sample length for impedance calculation	L = 0.08 mm	—	—	Text Approximate	5 · 2.4 Electrical Conductivity Measurements
parallel capacitance estimate	ca. 8 pF	—	—	Text Approximate	4-5 · 2.4 Electrical Conductivity Measurements · Figure 3C
Nyquist extrapolated resistance	~200 Ohm	—	—	Text Approximate	5 · 2.4 Electrical Conductivity Measurements · Figure 3C; Figure S9
estimated maximum initial sample height	0.08 mm	—	—	Text Approximate	S12 · 6. Impedance Measurements
sample closing capacitance fit	C_0 = 9.5 +/- 18 pF	—	+/- 18 pF	Visual Estimate Uncertain	S10 · Figure S7 annotation · Figure S7
capacitance increase due to samples	6 pF	—	—	Calculated From Reported Approximate	S13 · 6. Impedance Measurements
sample opening capacitance fit	C_0 = 2.5 +/- 0.7 pF	—	+/- 0.7 pF	Visual Estimate Uncertain	S10 · Figure S7 annotation · Figure S7
sample electrode-surface coverage	~10%	—	—	Text Approximate	S13 · 6. Impedance Measurements

2 measurement groups · 21 results