Effect of Temperature Gradient Direction in the Catalyst Nanoparticle on CNTs Growth Mode

Table 2 Specimen designations and their deposition conditions by plasma-enhanced CVD

Spec. desig.	Method ^a	W _pre / W_gro ^b (W/W)	Bias ^b V_pre / V_gro (V/V)	T _S ^b T _Si /T _Sf (°C/°C)	Dep. Time ^c (min)	∆T ^d	Growth Mode
B1	MP	800/800	100/120	467/500	5	+	Tip-growth
B2	MP	1,000/600	100/60	520/507	2	−	Base-growth
C1	ECR	250/270	100/120	500/530	5	+	Tip-growth
C2	ECR	300/240	120/100	750/631	4	−	Base-growth

^a MP Microwave plasma CVD, ECR Electron cyclotron resonance CVD, The working pressures in MP and ECR are 1.3 kPa and 0.9 Pa, respectively
^b W _pre, and V_pre = microwave power, and bias voltage during the H-plasma pre-treatment step (H₂ = 50 sccm), respectively
W _dep , V _dep, T _Si, and T_Sf = microwave power, bias voltage, initial and final substrate temperature of the deposition step (H₂/C₂H₂ flow ratio = 50/10 (sccm/sccm); pressure = 10 Torr), respectively
^c CNTs deposition time in minute
^d∆T = temperature of catalyst at the top minus at the bottom. Its sign represents the temperature gradient direction