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Thermoset Polymer Matrix–Based Natural Fiber Composites
Published in Shishir Sinha, G. L. Devnani, Natural Fiber Composites, 2022
Bismaleimide resin was made as a bridge to cover the temperature gap between polyimides and epoxy resin. The curing is done by an additional reaction at a higher temperature. They set free post-curing to accomplish polymerization reaction to obtain high thermal properties. They can undergo filament winding, autoclave curing, as well as resin transfer molding process. Their flip and mantle are better due to the presence of a liquid component of reactant. Bismaleimides are formed in two steps. The first step is the reaction of di-amines with maleic anhydride to form bismaleic acid. This is exothermic and fast and the second step is done by imidization. The most prevailing resin with base monomer for adhesives is 4,4′- bismaleimide diphenylmethane (Bao et al., 2001). Curing of bismaleimide can be done by either homopolymerization, which results in brittle fabrication or by copolymerization, which results in flexible and extended fabrication when reacted with diamine and toughening when reacted with olefins. Bismaleimide resin can be prepared by resin transfer molding and autoclave curing process. They are characterized by their properties like high-temperature polymerization, flexibility, toughening, and good thermal-oxidative behavior. A copolymerization reaction with discyanobidiscyan a resulted in BT resin, where B is bismaleimide and T is triazine. BCB (benzocyclobutene) exhibits toughness and good thermal behavior. Earlier, they were considered as less processing and low toughness, and with the modification they show better flip and good toughness.
Polymer Field-Effect Transistors
Published in Sam-Shajing Sun, Larry R. Dalton, Introduction to Organic Electronic and Optoelectronic Materials and Devices, 2016
In a standard MISFET device, the performance of the device may be increased by using the so-called high-k materials, insulators with a high dielectric constant ε. However, even if the number of charge carriers in the channel is increased and, thus, a better modulation of the current should be measured, this may in organic devices result in energy disorder at the interface due to a high dipole interaction. There are several reports where good performance has been achieved by using materials with a lower dielectric constant and where the purity of the material is emphasized, thus decreasing the disorder effect [107–109]. Benzocyclobutene (BCB) and its derivatives are currently the most commonly used materials in this context, as these may be produced with high purity and yield extremely thin pinhole-free films. In this case, the electronic performance is increased by the low thickness of the insulator layer and decreased interference by disorder. It has even been shown by using BCB as the gate dielectric that if the purity of the materials and the process are maintained, both p-type and n-type transistors may be made from RR-P3HT, a material where normally only p-type conduction may be seen [108]. The conclusion has been that electrons are very easily trapped by hydroxyl groups at the insulator–semiconductor interface when using PVP as the gate insulator, which is why only p-type transistors have been made using polymers with hydroxyl groups. Furthermore, BCB is a cross-linkable polymer allowing chemically and mechanically robust insulator films. BCB is even used as insulator material in amorphous silicon FETs where it outperforms silicon nitride as the gate insulator [110].
Impact of proton irradiation with different fluences on the characteristics of InP/InGaAs heterostructure
Published in Radiation Effects and Defects in Solids, 2019
Xiaohong Zhao, Hongliang Lu, Yuming Zhang, Yimen Zhang
The n-InP/P+-In0.53Ga0.47As heterostructure layers were grown by a gas source molecular beam epitaxy (GSMBE) on a p-InP substrate, in Shanghai Institute of Microsystem and Information Technology (SMIT). The arsenic and phosphorus beams were from thermal cracking of arsine (AsH3) and phosphine (PH3) at high temperature. Elemental gallium (Ga) and indium (In) were used as the group-III sources. Silicon (Si) and CBr4 (C) were used as n-type and p-type dopants, respectively. Figure 1 shows the layer sequence of n-InP/P+-In0.53Ga0.47As heterostructure, which consists of a 65-nm graded P+-InxGa1−xAs (C: 3 × 1019 cm−3) with x from 0.45 at the interface of n-InP/P+-In0.53Ga0.47As side to 0.53 at the P+-In0.53Ga0.47As/substrate side, a 40-nm n-InP layer (Si: 2 × 1017 cm−3), a 130-nm n-InP contact layer (Si: 1.2 × 1019 cm−3) and a 200-nm n-In0.53Ga0.47As cap layer (Si: 2 × 1019 cm−3). Benzocyclobutene (BCB) dielectric was used for passivation. The non-alloyed Ti/Pt/Au was taken as n-type ohmic contacts and the annealed Pt/Ti/Pt/Au was used as p-type ohmic contact, which was deposited by electron beam evaporation. At least ten devices were fabricated and tested under similar conditions, with similar results observed.