%AHong, Xia%BJournal Name: Science; Journal Volume: 374; Journal Issue: 6574 %D2021%I %JJournal Name: Science; Journal Volume: 374; Journal Issue: 6574 %K %MOSTI ID: 10313701 %PMedium: X %TNitride perovskite becomes polar %XThere is a strong drive behind the quest for thin-film materials that are oxygen-free and polar. Oxygen hinders the integration of ferroelectric oxides with semiconductors, which affects efforts to develop nonvolatile memory—that is, a memory that can sustain its information without power. Ideally, one would use single-crystalline perovskite films to construct these devices so that the polarization can be maximized. However, when depositing crystalline polar perovskite oxides onto silicon or germanium, a nonpolar oxide buffer layer ( 1 ) or a native oxide layer ( 2 ) can be present at the interface, compromising device performance. A nitrogen-based perovskite may overcome this limitation ( 3 ). On page 1488 of this issue, Talley et al. ( 4 ) report the synthesis of lanthanum tungsten nitride (LaWN 3 ) thin films, which marks the first demonstration of polar nitride perovskite. This may lead to oxygen-free integration of functional perovskite on a semiconductor platform. %0Journal Article