Spike-notch structure of (AlGa)As heterojunctions

Petrescu-Prahova, I.B.; Mihailovici, P.; Nache, C.; Constantinescu, C.; Haecker, W.

doi:10.1109/t-ed.1976.18343

Cited by 5 publications

(1 citation statement)

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“…A closer look at the values of the ideality factor evidenced that they largely depend on the material used as an anode contact. To some extent, these values are also influenced by the LUMO and HOMO band offsets that generate these notch-spike type discontinuities or the berries between the metal and semiconductor junctions at the level of which the electrons or the holes must tunnel (field emission) or “jump” over the barriers (thermoemission) through an accumulation–recombination mechanism in the space-charge region , (as highlighted by the red circles in Figure ). Mainly, this aspect is not the one responsible for the variation of the ideality factor and rather by the material used as the anode.…”

Section: Resultsmentioning

confidence: 99%

Assessing the Electrical Characteristics of p–n Heterojunction Prototype Diodes Realized with n-Type Polyimide Materials

Constantin¹,

Lisă

Damaceanu³

2021

Macromolecules

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Three new aromatic polyimides with donor–acceptor topology consisting of electron-donating ortho-catenated triphenylamine (TPA) modified with two trifluoromethyl (CF3) groups and electron-accepting naphthyl(di)imide- or perylenediimide-based moieties were synthesized and thoroughly investigated. Their main physicochemical properties were assessed according to the structural variation of the dianhydride segment. The polymers exhibited advantageous solubility in polar solvents, which allowed their processing into homogeneous thin films under friendly conditions, as well as good thermal stability. The photo-optical activity investigated in detail by UV–vis and fluorescence spectroscopy was finely modulated by the electron-accepting strength of the dianhydride segment, with light emission originating from both monomeric and intramolecular charge transfer transitions, which is otherwise dependent on the polarity of the surrounding solvent molecules. Due to the high electron-accepting characteristics promoted by both CF3 and naphthyl(di)imide or perylenediimide, these polymers behaved as n-type materials. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energies evaluated according to the electrochemical activity suggested the polymers suitability for use in p–n heterojunctions. Thus, to prove the electron transporting capability, prototype diodes have been realized with these polyimides in an indium tin oxide (ITO)(Al)/poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS)/polyimide/eGaIn configuration. Their current–voltage characteristics revealed a rectification ratio up to 63, moderate to high shunt resistance, moderate to low series resistance, and moderate current leakages. The charge transport evaluation disclosed the tunneling phenomenon as the main mechanism that drives the realized prototype diodes, with an ideality factor down to 5.48. The nice combined features encountered for these polyimides make them appealing candidates as n-type materials for advanced optoelectronic applications.

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Section: Resultsmentioning

confidence: 99%