made up of programmable circuitry as well as biocompatible electrodes and wires. The self-

degradation of implanted devices in biofluids benefits through reducing the medical

treatment cost and also risk associated with it. Flexible implanted devices achieve self-

degradation by using relevant semiconducting materials. Silicon, along with Ge and ZnO, is

one of the most widely utilized bioresorbable semiconductor materials for making soft

electronics that are implanted temporarily [19]. Wide bandgap bioelectronics have also

been applied in a versatile field, with long-lasting electronics, nano energy storage, bior­

esorbable machinery, printable and implantable devices, and optogenetic devices. [20].

12.2 Semiconducting Materials and Their Advantages for Bioelectronics

12.2.1 Wide Bandgap-Based Materials for Bioelectronics

Silicon has drawbacks such as degradation in biofluids, fast ion diffusion, etc. Due to

these disadvantages, Si is inappropriate for wearable and implantable uses. Also, due to

low piezoelectric coefficient and indirect bandgap of silicon limit itself in soft energy

harvesting applications. The wide bandgap (WBG) materials have been the point of at­

traction due to superior chemical and physical properties over silicon [20]. Herein, we

summarize alternative semiconducting materials of the class like IV–IV, III–V, and II–VI.

The bandgap of these materials is greater than 2 eV and can be used for a high breakdown

electric field. Also, it enhances the durability of devices due to the strong covalent bond in

the atoms of WBG nanomaterials.

The II-VI class of the materials is made up of second group elements and six group

chalcogen elements. This class of materials was explored for optoelectronics. One of the

prominent materials in this group is zinc oxide. ZnO is popular due to its piezoelectricity,

biodegradability, and direct WBG nature. Dagdeviren et al [16] reported that zinc oxide

is soluble in demineralized H2O at a normal temperature in 15 hours and shows no evi­

dence after the method. In addition to this test, ZnO show in vitro biocompatibility cell

culture assays test so it is useful for wearable and implantable uses due to its biocompat­

ibility (Figure 12.1) [21]. SiC is another class of the WBG semiconducting material for

FIGURE 12.1

Biocompatibility test of ZnO nanowires at 12 hours, 24 hours, 48 hours: (a) Hela cell line in vitro viability cell

(MTT) test and (b) viability of L929 cell line in MTT test. Adapted with permission [ 21]. Copyright 2008,

American Chemical Society.

Semiconducting Nanostructured Materials

189