DiffusjonDrift - + Diffusjon Drift

Solid State Electronic Devices, 7e, Global Edition Ben G. Streetman | Sanjay Kumar Banerjee Copyright © Pearson Education Limited All rights reserved. Figure 8–1 Optical generation of carriers in a p-n junction: (a) absorption of light by the device; (b) current I op resulting from EHP generation within a diffusion length of the junction on the n side; (c) I–V characteristics of an illuminated junction. Fotodiode

Solid State Electronic Devices, 7e, Global Edition Ben G. Streetman | Sanjay Kumar Banerjee Copyright © Pearson Education Limited All rights reserved. Figure 8–3 Operation of an illuminated junction in the various quadrants of its I–V characteristic; in (a) and (b), power is delivered to the device by the external circuit; in (c) the device delivers power to the load. Fotodiode – 3 hovedtyper LED Foto- detektor Solcelle

Solid State Electronic Devices, 7e, Global Edition Ben G. Streetman | Sanjay Kumar Banerjee Copyright © Pearson Education Limited All rights reserved. Figure 8–5 Configuration of a solar cell: (a) enlarged view of the planar junction; (b) top view, showing metal contact “fingers.”

Mastering of Si-based heterojunction thin film solar cells having TCO electrodes Generic illustration of issues addressed in one of SMN’s main solar research programs (TCO = Transparent Conductive Oxide, ITO = Indium-Tin-Oxide, a-Si:H = amorphous hydrogenated Si) Nanocrystal

Indium-Tin-Oxide films as T ransparent C onductive O xide Balasundaraprabhu, Monakhov et al., Mat. Chem. Phys. 114, 425 (2009) High optical transmission (in the visible range) and high electrical conductivity Resistivity (Ωcm) ZnO(Ga): 1x10 -4 Ωcm Look, Leedy, Vines et al. (PRB 2011)

Solar United – Si/oxide solar cell Shunt resistance: excellent Serial resistance: OK Fill factor=75%: good J sc =30 mA/cm 2 : poor-to-OK V oc =0.55 V: poor (!) Efficiency: ~14 % ICT/Department of Microsystems and Nanotechnology

Solid State Electronic Devices, 7e, Global Edition Ben G. Streetman | Sanjay Kumar Banerjee Copyright © Pearson Education Limited All rights reserved. Figure 8–6 I–V characteristics of an illuminated solar cell. The maximum power rectangle is shaded. P max = I m V m

Perovskite = CH 3 NH 3 PbX 3 ; X= I or Br

Tandem junction solar cell; oxide + silicon We use more photons and loose less energy ZnCuO-cell p-Cu 2 O p + -Cu 2 O

Zinc atom Electron We use more photons and loose less energy Silicon atom ‘NanoCrystal’ (NC) Oxygen atom ZnO and nanocrystals ?

Si-nanocrystals in ZnO films HRTEM image of Si nanocrystals imbedded in a sputtered ZnO(Si) film Schofield, Schifano et al., in progress Dark field image of a sputtered ZnO(Si) film

Solid State Electronic Devices, 7e, Global Edition Ben G. Streetman | Sanjay Kumar Banerjee Copyright © Pearson Education Limited All rights reserved. Figure 8–7 Schematic representation of a p-i-n photodiode. Pin-detektor

Eks: Si Eks: GaAs  k=0 k≠0k≠0

Figure 8.10 Conduction band energies as a function of alloy composition for GaAs 1-x P x LED-materialer Direct E g Indirect E g