Hybrid phase-change memristors lead to new computing possibilities
By strategically straining materials that are as thin as a single layer of atoms, University of Rochester scientists have developed a new form of computing memory that is at once fast, dense, and low-power. The researchers outline their new hybrid resistive switches in a study published in Nature Electronics.
Developed in the lab of Stephen M. Wu, an assistant professor of electrical and computer engineering and of physics, the approach marries the best qualities of two existing forms of resistive switches used for memory: memristors and phase-change materials. Both forms have been explored for their advantages over today's most prevalent forms of memory, including dynamic random access memory (DRAM) and flash memory, but they have their drawbacks.
Wu says that memristors, which apply voltage to a thin filament between two electrodes, tend to suffer from a relative lack of reliability compared to other forms of memory. Meanwhile, phase-change materials, which involve selectively melting a material into either an amorphous state or a crystalline state, require too much power.
"We've combined the idea of a memristor and a phase-change device in a way that can go beyond the limitations of either device," says Wu. "We're making a two-terminal memristor device, which drives one type of crystal to another type of crystal phase. Those two crystal phases have different resistance that you can then store as memory."
The key is leveraging 2D materials that can be strained to the point where they lie precariously between two different crystal phases and can be nudged in either direction with relatively little power.
"We engineered it by essentially just stretching the material in one direction and compressing it in another," says Wu. "By doing that, you enhance the performance by orders of magnitude. I see a path where this could end up in home computers as a form of memory that's ultra-fast and ultra-efficient. That could have big implications for computing in general."
Wu and his team of graduate students conducted the experimental work and partnered with researchers from Rochester's Department of Mechanical Engineering, including assistant professors Hesam Askari and Sobhit Singh, to identify where and how to strain the material. According to Wu, the biggest hurdle remaining to making the phase-change memristors is continuing to improve their overall reliability—but he is nonetheless encouraged by the team's progress to date.
More information: Wenhui Hou et al, Strain engineering of vertical molybdenum ditelluride phase-change memristors, Nature Electronics (2023). DOI: 10.1038/s41928-023-01071-2
Kwa kutumia nyenzo nyembamba kama safu moja ya atomu, wanasayansi wa Chuo Kikuu cha Rochester wamebuni aina mpya ya kumbukumbu ya kompyuta ambayo ni ya haraka, nzito, na ya nguvu ya chini. Watafiti wanaelezea viunganishi vyao vipya vya msuguano katika utafiti uliochapishwa katika Nature Electronics. "Mfano wa ""switch"" ni mbinu ya Stephen M. Wu, profesa msaidizi wa uhandisi wa umeme na kompyuta na fizikia, ambayo inaunganisha sifa bora za aina mbili zilizopo za swichi za upinzani zinazotumiwa kwa kumbukumbu: memristors na vifaa vya mabadiliko ya awamu." Aina zote mbili za kumbukumbu zimekuwa zikichunguzwa kwa sababu ya faida zao juu ya aina za kumbukumbu za leo, ikiwa ni pamoja na kumbukumbu ya upatikanaji wa random (DRAM) na kumbukumbu ya flash, lakini zina hasara zao. "Wu anasema kwamba memristors, ambayo hutumia voltage kwa filament nyembamba kati ya electrodes mbili, huwa na kuteseka kutokana na ukosefu wa uaminifu ikilinganishwa na aina nyingine ya kumbukumbu. """ Wakati huo huo, vifaa vya mabadiliko ya awamu, ambavyo vinahusisha kuyeyuka kwa kuchagua nyenzo katika hali ya amorphous au hali ya kioo, inahitaji nguvu nyingi sana. "Tumejumuisha wazo la memristor na kifaa cha mabadiliko ya awamu kwa njia ambayo inaweza kwenda zaidi ya mapungufu ya kifaa chochote", anasema Wu. "Tunafanya kifaa cha memristor cha mwisho mbili, ambacho husababisha aina moja ya kioo kwenda aina nyingine ya awamu ya kioo. Hatua hizo mbili za kioo zina upinzani tofauti ambao unaweza kuhifadhiwa kama kumbukumbu". "Kifungu ni kutumia vifaa vya 2D ambavyo vinaweza kushinikizwa hadi hatua ambapo vinakaa kwa hatari kati ya awamu mbili tofauti za kioo na vinaweza kusukumwa katika mwelekeo wowote na nguvu ndogo.""" "Tuliunda kwa kunyoosha tu nyenzo hiyo katika mwelekeo mmoja na kuifunga katika mwelekeo mwingine", asema Wu. "Kwa kufanya hivyo, unaongeza utendaji kwa utaratibu wa ukubwa. "Kama vile tunavyoona, hii inaweza kuwa ""mwisho"" katika kompyuta za nyumbani kama aina ya kumbukumbu ambayo ni ya haraka sana na yenye ufanisi sana." Hilo laweza kuwa na matokeo makubwa kwa kompyuta kwa ujumla". Wu na timu yake ya wanafunzi wa kuhitimu walifanya kazi ya majaribio na kushirikiana na watafiti kutoka Idara ya Uhandisi wa Mashine ya Rochester, pamoja na maprofesa msaidizi Hesam Askari na Sobhit Singh, kutambua wapi na jinsi ya kusonga nyenzo. Kulingana na Wu, kizuizi kikubwa kinachobaki kutengeneza memristors za mabadiliko ya awamu ni kuendelea kuboresha kuegemea kwao kwa ujumla - lakini hata hivyo anachochewa na maendeleo ya timu hadi sasa. Habari zaidi: Wenhui Hou et al, Strain uhandisi wa wima molybdenum ditelluride awamu-kubadilisha memristors, Nature Electronics (2023). (Kwanza: 1038-S41923-01072)