Laser sintered PbSe semiconductor thin films for Mid-IR applications using nanocrystals

Interests in group IV-VI compound semiconductors for MWIR applications have undergone multiple resurgences over the last 70 years due to the high IR responsivity. Many research groups have shown they can achieve high IR response by making modification of the sensitization process; however, nearly all are using traditional deposition methods (Chemical Bath Deposition or Chemical/Physical Vapor Deposition) involving complex chemical processing or vacuum-based equipment. This work introduces a flexible alternative method for producing ultrapure polycrystalline thin films with exceptional morphological control. The process utilizes a planetary ball-mill to wet-mill ultra-pure crystalline ingot into colloidal nanocrystals (NC), followed by rapid deposition in a centrifuge to form a compact, thin film across a silicon substrate. Laser sintering is then used to rapidly form a continuous denser film with excellent substrate adhesion and unique control of the morphological properties. This work demonstrates a new method using laser sintering that can form a 1.5 mu m thin film of PbSe with equivalent physical and electrical (p-type with a carrier concentration of 4.5 x 10(17)/cm(3) and resistivity value of 0.17 Omega cm) properties to CBD/PVD. The results are presented for the process development, film morphology, crystal structure, and electrical properties. Lastly, unlike traditional deposition methods, this alternative process is environmentally responsible by producing zero hazardous waste by allowing recovery of all unused PbSe for reuse. The reported method is applicable for achieving thin films from a variety of high purity bulk materials. (C) 2020 Elsevier B.V. All rights reserved.