Fig. 1: CuInSe2 CQD-based p-channel FETs.
From: Solution-processable integrated CMOS circuits based on colloidal CuInSe2 quantum dots
a A representative transmission electron microscopy (TEM) image (scale bar is 10 nm) of CuInSe2 colloidal quantum dots (CQDs). The CQDs have a nearly spherical shape and are characterized by an average diameter of 7.3 ± 1.9 nm. A high-resolution (HR) TEM image of an individual CQD (lower inset) and a diffractogram of a “boxed” region obtained using a fast Fourier transform (upper inset) indicate the high crystallinity of the synthesized particles. b A schematic depiction of a CuInSe2 CQD with the different types of surface ligands used in this study. As-synthesized CuInSe2 CQDs are capped with molecules of oleylamine (OLAm) and diphenylphosphine (DPP). For carrier transport studies, the bulky native ligands are replaced with shorter species that include ethanedithiol (EDT), NH4Cl, NH4I, and NH4Br. c A schematic diagram of a bottom-gate, bottom-contact CQD-field-effect transistor (FET). In p-channel FETs, source and drain electrodes are made of gold (100 nm thickness) deposited by thermal evaporation on top of a SiO2/p++ Si substrate (the thickness of the SiO2 layer is 300 nm). The channel dimensions are 3 mm (width) × 100 µm (length). CuInSe2 CQDs are deposited by spin-coating onto the prepatterned electrodes, and the original surface ligands are exchanged for EDT, NH4Cl, NH4I, or NH4Br. Output characteristics (IDS vs. VDS) of Au-contact FETs fabricated from CuInSe2 CQDs with different types of surface ligands: EDT (d), NH4Cl (e), NH4I (f), and NH4Br (g). All devices were annealed at 180 °C for 1 h. The applied gate-source voltages (VGS) are indicated in the legends. Source data are provided as a Source Data file.
