Optoelectronics with Carbon Nanotubes
Optoelectronics with Carbon Nanotubes Optoelectronics with Carbon Nanotubes
(a) (c) (d) Figure III-16. EL spectra of the double-peak sample (same as in Figure III-13) through a linear polarizer (a) aligned with and (b) perpendicular to the tube direction, respectively. Note the arrow in (b) indicating emission from the E12 excitonic transition. (c), (d) Normalized EL intensity from the same data as from (a) and (b) with the E11 and E22 double-peak fit subtracted. Solid lines are lorentz fits. If there is no solid line, a reasonable Lorentz function could not be determined. 65 (b)
3. Conclusions We have examined the intensity and spectral shapes of EL from single-tube CNTFETs. From transport measurements, it is seen that their electrical transfer depends on the control of Schottky barriers at metal contacts. In agreement with an impact-excitation process of exciton generation, a threshold behavior is observed at the EL onset. The very broad lineshape of the E11 transition is attributed to tube non-homogeneity, phonon scattering, electronic heating, and the effect of external electric field in the longitudinal direction. There is evidence that phonon temperatures (and with it, possibly electron temperatures) saturate at very high input power, possibly because of the energy dissipation by the EL mechanism. We have observed E11 and E22 peaks, defect-mediated E11 peak, and the E11 - optical phonon side band complex. In polarized measurements, a clear suppression of E11 and E22 peaks is observed in the perpendicular direction. Conversely, we were able to observe the E12 transition for the first time in EL by investigating perpendicularly polarized component of the emission. Our data point to possible future explorations that include phonon and electron temperature measurements, a more detailed investigation of the broadening mechanisms, and a realization of better signal-to-noise ratio for superior spectroscopic data. While polarized EL from CNT may have interesting applications in future nano-scale optoelectronics, there are many issues, especially in carrier and phonon dynamics and their interactions, that still need to be better understood. 66
- Page 27 and 28: The disorder-induced band (D-band)
- Page 29 and 30: The saturation limit for semiconduc
- Page 31 and 32: (a) (b) Figure I-7. (a) A schematic
- Page 33 and 34: assisted tunneling through Schottky
- Page 35 and 36: majority carriers that gain enough
- Page 37 and 38: conventional ambipolar emission. Th
- Page 39 and 40: on quartz, which remains a signific
- Page 41 and 42: Chapter II Methods 1. Materials One
- Page 43 and 44: diameter (< 2 nm) SWNTs at IBM T. J
- Page 45 and 46: devices were annealed in vacuum at
- Page 47 and 48: 3. Experimental set-up The optical
- Page 49 and 50: off wavelengths of 2150 nm, 2000 nm
- Page 51 and 52: Chapter III Unipolar, High-Bias Emi
- Page 53 and 54: Figure III-1. Semi-log plot of drai
- Page 55 and 56: wetting with CNTs 57 and a relative
- Page 57 and 58: Figure III-4. (Main panel) Electrol
- Page 59 and 60: By plotting the current as a functi
- Page 61 and 62: phonon temperature in broadening. S
- Page 63 and 64: found multiple tubes bound together
- Page 65 and 66: where i is the phonon mode, Tsub is
- Page 67 and 68: The main panel of Figure III-10 sho
- Page 69 and 70: the effect following Perebeinos’
- Page 71 and 72: the optical phonon population is no
- Page 73 and 74: (a) Figure III-13. (a) Spectra from
- Page 75 and 76: DOP = I║ / (I┴ + I║) = 0.77.
- Page 77: inding energy for perpendicular exc
- Page 81 and 82: In a split-gate scheme, a new level
- Page 83 and 84: 3. Electroluminescence mechanism an
- Page 85 and 86: After calibrating our detection sys
- Page 87 and 88: (a) (b) Figure IV-3. Electrolumines
- Page 89 and 90: observed by increasing the VGS valu
- Page 91 and 92: We claimed in Chapter III that in t
- Page 93 and 94: Let us finally comment on the effic
- Page 95 and 96: Chapter V The Polarized Carbon Nano
- Page 97 and 98: (a) (b) Figure V-1. (a) SEM image o
- Page 99 and 100: oth electrons and holes can be inje
- Page 101 and 102: In the reverse direction (i.e., neg
- Page 103 and 104: 4. Electroluminescence characterist
- Page 105 and 106: and drain pads (marked “S” and
- Page 107 and 108: (a) (b) Figure V-8. (a) EL intensit
- Page 109 and 110: We attribute the observation of the
- Page 111 and 112: (a) (b) (c) Figure V-9. Electrolumi
- Page 113 and 114: measurements (i.e. additional chemi
- Page 115 and 116: (a) (b) Figure V-10. Full-width at
- Page 117 and 118: mechanisms are the same for differe
- Page 119 and 120: experiment, solid line: cosine squa
- Page 121 and 122: emission observed at higher current
- Page 123 and 124: Bibliography 1. Avouris, P.; Chen,
- Page 125 and 126: 30. Miyauchi, Y.; Maruyama, S., Ide
- Page 127 and 128: 56. Chen, Z.; Appenzeller, J.; Knoc
(a)<br />
(c) (d)<br />
Figure III-16. EL spectra of the double-peak sample (same as in Figure III-13)<br />
through a linear polarizer (a) aligned <strong>with</strong> and (b) perpendicular to the tube direction,<br />
respectively. Note the arrow in (b) indicating emission from the E12 excitonic<br />
transition. (c), (d) Normalized EL intensity from the same data as from (a) and (b)<br />
<strong>with</strong> the E11 and E22 double-peak fit subtracted. Solid lines are lorentz fits. If there is<br />
no solid line, a reasonable Lorentz function could not be determined.<br />
65<br />
(b)
Change language