tag:blogger.com,1999:blog-13869903.post3898195731874107492..comments2024-03-28T04:15:44.459-05:00Comments on nanoscale views: Oxide interfaces for fun and profitDouglas Natelsonhttp://www.blogger.com/profile/13340091255404229559noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-13869903.post-45225613957561192692016-04-28T04:27:36.304-05:002016-04-28T04:27:36.304-05:00https://www.princeton.edu/~joha/Johannes_Haushofer...https://www.princeton.edu/~joha/Johannes_Haushofer_CV_of_Failures.pdfAnonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-15461695996041471032016-04-27T11:14:14.749-05:002016-04-27T11:14:14.749-05:00http://phys.org/news/2016-04-scientists-quantum-ph...http://phys.org/news/2016-04-scientists-quantum-physics-real-life.html<br /><br />Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-84222763110280481372016-04-25T16:04:00.201-05:002016-04-25T16:04:00.201-05:00The LAO-STO interface is amazingly complex, but it...The LAO-STO interface is amazingly complex, but it's also ripe with inconsistencies. How you prepare the samples matters a ton, because it's been shown pretty conclusively IMO that the conductivity is all defect driven. Papers by Lane Martin's group, Darrell Schlom's group and various others have looked at the role of the synthesis process in getting the properties and shown that it only happens in the case of LaAlO3 films that don't have La:Al 1:1 ratios. Levy's group and many others have done some remarkable science on the defect-induced 2DEGs, but I think the polar catastrophe model has been pretty conclusively disproven. Anonymoushttps://www.blogger.com/profile/13402090762375371310noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-66533905286395318852016-04-25T10:47:33.165-05:002016-04-25T10:47:33.165-05:00This paper explains a bit more about the nature of...This paper explains a bit more about the nature of doping in the III-N system: http://scitation.aip.org/content/aip/journal/jap/87/1/10.1063/1.371866Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-5484397885575267202016-04-25T10:45:49.341-05:002016-04-25T10:45:49.341-05:00Prof. Natelson, it's true that you don't g...Prof. Natelson, it's true that you don't get a 2-DEG at an AlGaAs/GaAs interface without gating or doping the AlGaAs layer but that is not necessarily true for AlGaN/GaN. You end up with a 2-DEG at that interface due to polarization effects and some unintentional doping from defects. Would you say that the III-N system is similar to the LAO/STO system in that case? The 2-DEG density is certainly lower for III-N systems (1-2e13).Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-5676738523994154882016-04-25T08:34:33.429-05:002016-04-25T08:34:33.429-05:00Anon@10:53, a couple of things. There are multipl...Anon@10:53, a couple of things. There are multiple bands involved including d-bands, while conventional III-V 2deg or group IV 2deg is based only on s and p. Also, the dielectric function of STO is pretty wild (very large in the dc limit, tending in the direction of divergence at T = 0). <br /><br />Ted, cool. Yeah, STO can be doped (as can other oxide semiconductors, of course, like TiO2 or ZnO), and you have a point about overselling. Still, you don't get a 2deg at the GaAs/AlGaAs interface without gating unless you deliberately dope, where the LAO/STO case seems to happen without deliberate doping (b/c of the need to avert the polar catastrophe? This isn't really my direct area of research, so I haven't kept up on this as much as I should have.). <br /><br />Anon@7:27, yes, to echo Ted. Indeed, this has been a major challenge in understanding these systems - you want to make sure you can tell the difference between intrinsic effects and effective doping due to unintentional defect formation at or near the interfaces.<br />Douglas Natelsonhttps://www.blogger.com/profile/13340091255404229559noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-44792518900283514442016-04-25T07:27:04.151-05:002016-04-25T07:27:04.151-05:00It is indeed very simple to “convert” SrTiO3 to an...It is indeed very simple to “convert” SrTiO3 to an electron “conductor”: A short annealing under vacuum conditions or in reducing atmospheres generates oxygen vacancies which act as donors (induced self-doping by reduction).Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-13869903.post-26786251283104292672016-04-25T02:17:41.806-05:002016-04-25T02:17:41.806-05:00"Despite the fact that both of those parent c..."Despite the fact that both of those parent constituents are band insulators, the interface between the two was found to play host to a two-dimensional gas of electrons with remarkable properties. The wikipedia article linked above is pretty good, so you should read it if you're interested.<br /><br />When you think about it, this is really remarkable. You take an insulator, and another insulator, and yet the interface between them acts like a metal."<br /><br />Sometimes I worry that the LAO/STO people oversell this "remarkable" fact. I'd call STO a semiconductor rather than an insulator (it can be doped n-type with impurities, after all), so viewed from that perspective, I don't think it's super surprising that it can be modulation-doped to host an n-type 2DEG. Anyway, I suppose it's all a matter of perspective.<br /><br />P.S. I wrote the Wikipedia article on LAO/STO and I'm glad you liked it.Ted Sandershttps://www.blogger.com/profile/15001183656827732917noreply@blogger.comtag:blogger.com,1999:blog-13869903.post-87010906502023181802016-04-24T22:53:01.952-05:002016-04-24T22:53:01.952-05:00Thanks for the write up!
If I understand it corr...Thanks for the write up! <br /><br />If I understand it correctly, the LTO/STO interface hosts a two-dimensional electron gas. What makes it different from other well known systems that host 2D electron gases? Anonymousnoreply@blogger.com