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Here, we report the direct, atomic-scale visualization of polarization-induced electric fields at Ga-polar InGaN\/GaN heterointerfaces using four-dimensional scanning transmission electron microscopy. Contrary to the classical approximation of an abrupt sheet charge, our measurements reveal a spatially delocalized negative charge accumulation biased toward the GaN barrier. Complementary electron energy-loss spectroscopy and density functional theory calculations identify the microscopic origin of this asymmetry: the incorporation of indium weakens the local metal-to-nitrogen charge donation and enhances electronic delocalization, thereby reshaping the interfacial electrostatic potential. These findings demonstrate that the polarization charge is an intrinsic, chemically modulated volume property rather than a simple boundary condition, providing critical insights for accurate modeling of carrier confinement in nitride devices.<\/jats:p>","DOI":"10.1021\/acsami.6c11490","type":"journal-article","created":{"date-parts":[[2026,7,10]],"date-time":"2026-07-10T11:02:47Z","timestamp":1783681367000},"page":"42204-42211","source":"Crossref","is-referenced-by-count":0,"title":["Direct Observation of Asymmetric Interfacial Charge Distribution in InGaN\/GaN Heterostructures"],"prefix":"10.1021","volume":"18","author":[{"given":"Haowei","family":"Yang","sequence":"first","affiliation":[{"name":"Central South University , , , ,","place":["Changsha, Hunan, P.R. China, 410083"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xiang","family":"Huang","sequence":"additional","affiliation":[{"name":"Yangzhou University , , ,","place":["Jiangsu, P.R. China, 225009"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7582-4456","authenticated-orcid":true,"given":"Zhe","family":"Zhang","sequence":"additional","affiliation":[{"name":"Yangzhou University , , ,","place":["Jiangsu, P.R. China, 225009"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yang","family":"Qiu","sequence":"additional","affiliation":[{"name":"Southern University of Science and Technology , , ,","place":["Shenzhen, P.R. China, 518055"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lei","family":"Chen","sequence":"additional","affiliation":[{"name":"Monash University , , , ,","place":["Melbourne, VIC, Australia, 3800"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-9958-1666","authenticated-orcid":true,"given":"Qi","family":"Wang","sequence":"additional","affiliation":[{"name":"City University of Hong Kong , , ,","place":["Hong Kong, P.R. 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