Epitaxial liftoff technology epitaxial liftoff technology yablonovitch, eli 19911201 00. The epi layer may be the same material as the substrate, typically monocrystaline silicon, or it may be a more exotic material with specific desirable qualities. A method for performing epitaxial liftoff allowing reuse of a iiiv substrate to grow iiiv devices is presented. Embodiments of the invention generally relate to apparatuses and methods for producing epitaxial thin films and devices by epitaxial lift off elo processes. Novel epitaxial liftoff elo with enabling direct reuse. With the modified elo method crackfree iiiv films were obtained, up to 2 inch, in diameter and 16.
The technique has also been applied to iivi samples onto which dielectric films had been deposited. Off elo technique, which is used to separate iiiv device. Ultraefficient epitaxial liftoff solar cells exploiting. Chris youtsey, microlink devices, inc robert mccarthy. Vi samples onto which dielectric films had been deposited. Photoluminescence measurements show that the material quality has not been degraded. In this study, the thinfilm verticaltype algainp leds on cu substrates were fabricated. Liftoff of freestanding layers in the kerfless porous. Mechanical flexibility of electronic devices has attracted much attention from research due to the great demand in practical. Epitaxial liftoff process for gallium arsenide substrate reuse and. Osa thinfilm verticaltype algainp leds fabricated by. Epitaxial liftoff epitaxial liftoff elo then called peeled film techno logy was first reported by konagai et al in 1978 io, and it showed the possibility of grafting gaas solar cells onto an a1 plate.
We introduce a novel germaniumonnothing gon technology to fabricate ultrathin ge films for lightweight and thin gaas solar cells. We describe the use of the epitaxial liftoff technique to remove thin layers of inas from the gaas substrates on which they were grown and subsequently bonded to glass and silicon substrates. Epitaxial liftoff technique has been explored for the fabrication of costeffective solar cells because of easy separation of iiiv device layers from the gaas substrate and hence, enables. Interest in thin film grafting techniques has increased rapidly recently, mainly due to the difficul.
The presence of the release layer permits the solar cell epitaxial structure to be removed from the substrate without damage. Epitaxial liftoff process enables the separation of iiiv device layers from gallium arsenide substrates and has been extensively explored to avoid the high cost of iiiv devices by reusing. Germaniumonnothing for epitaxial liftoff of gaas solar. Epitaxial liftoff process enables the separation of iiiv device layers from gallium arsenide substrates and has been extensively explored to. Etching of siox with 5% hf allows epitaxial lift off of the copper film, giving single crystallike cu100 foils.
Epitaxial liftoff of films on singlecrystal substrates by dissolving a sacrificial adhesion layer can produce freestanding singlecrystal foils. Epitaxial nacl can serve as a watersoluble template for largescale epitaxial liftoff of flexible singlecrystallike materials for electronics, solar cells, and displays. In this paper the authors will give an overview of the epitaxial liftoff elo technique and its applications. Therefore, a high conversion efficiency is expected because the lattice mismatch is not a problem. Finally, lifting off a material is an option if there is no access to an etching tool with the appropriate gases. Hubbard, associate professor thesis advisor, department of physics and microsystems engineering dr. Department of energy laboratory operated by midwest research institute battelle bechtel. As an alternative technique, the epitaxial liftoff elo process has been studied. This study reports on a novel vacuum epitaxial liftoff velo process to reuse the gaas substrates in lightemitting diode led production. Ultraefficient epitaxial liftoff solar cells exploiting optical confinement in the wave limit final technical report 19 july 1994 18 july 1998 national renewable energy laboratory 1617 cole boulevard golden, colorado 8040393 nrel is a u. Epitaxial liftoff and wafer bonding for iiiv photodetectors on silicon.
A sample is received comprising a growth substrate with a top surface, a sacrificial layer on the top surface, and a device layer on the sacrificial layer. Dryepitaxial liftoff for high efficiency solar cells ieee conference. Application of epitaxial liftoff to optoelectronic. Quantum dot enhanced epitaxial liftoff solar cells by mitchell f. Advanced epitaxial liftoff quantum dot photovoltaic devices. An epitaxial wafer also called epi wafer, epiwafer, or epiwafer is a wafer of semiconducting material made by epitaxial growth for use in photonics, microelectronics, spintronics, or photovoltaics. Compared with previous porous ge studies, we significantly improve the surface quality of reformed ge by engineering.
Off for large area thin film iiiv devices schermer. Chapter 3 hybrid integration using the epitaxial lift off method 3. In the present work the space compatibility of thin. A metal backing layer is first applied to the solar cell structure in order to provide mechanical support for the solar cell after liftoff. In one embodiment, a method for forming thin film devices during an elo process is provided which includes coupling a plurality of substrates to an elongated support tape, wherein each substrate contains an epitaxial film disposed over a. Epitaxial synonyms, epitaxial pronunciation, epitaxial translation, english dictionary definition of epitaxial. Epitaxial definition of epitaxial by the free dictionary. Scaled spinel ferrite oxide thin films for flexible electronics. Yablonovitch march 1990 updated may 1996 a introduction epitaxial liftoff elo permits the integration of illv films and devices onto arbitrary material substrates. Electrodeposited epitaxial cu100 on si100 and liftoff. Us10204831b2 tapebased epitaxial lift off apparatuses. Germanium layer transfer with epitaxial liftoff technique. Abstract the present work describes the study and improvement of the epitaxial lift. The epitaxial lift off process allows the separation of a thin layer of iii v material from the substrate by selective etching of an intermediate alas layer with hf.
Epitaxial liftoff for iiinitride devices sciencedirect. Accelerated lifetime testing elevated temperature and thermal cycling to design for 25 yr lifetime. Epitaxial lift off of films on singlecrystal substrates by dissolving a sacrificial adhesion layer can produce freestanding singlecrystal foils. Epitaxial lift off epitaxial lift off elo then called peeled film techno logy was first reported by konagai et al in 1978 io, and it showed the possibility of grafting gaas solar cells onto an a1 plate.
Tian lan and guoqiang ni photoconductive switch using epitaxial liftoff lowtemperaturegrown gaas. One method for the processing of thin solar cells that has been experimentally demonstrated on large 46 wafers is epitaxial liftoff, which takes advantage of an inverted growth and a wet chemical etch of a sacrificial release layer to remove the substrate. Epitaxial liftoff technology, proceedings of spie 10. Pdf the epitaxial lift off process allows the separation of a thin layer of iii v material from the substrate by selective etching of an. A novel vacuum epitaxial liftoff velo process for separation of. This translates to an increasing quality of epitaxy with increasing thickness.
Then the gaas substrate was separated and the eloled was completed. A support handle may be disposed on the opposite side of the epitaxial material than the substrate. Etching of siox with 5% hf allows epitaxial liftoff of the copper film, giving single crystallike cu100 foils. A dry epitaxial liftoff delo process is presented by driving a controlled crack at the epiwafer interface and transferring wafer scale to a polyimide substrate. Quantum dot enhanced epitaxial liftoff solar cells by. Epitaxial liftoff process for gallium arsenide substrate. We have discovered conditions for the selective lift.
This first part will describe the basic technology, which includes chemical liftoff, handling bonding, stress, alignment, etc. Vertical devices are advantageous for power applications because they can utilize thick lowdoped drift layers to achieve higher breakdown voltages. Epitaxial liftoff of thin inas layers springerlink. The epitaxial liftoff procedure for ultrathin singlecrystal foils of au electrodeposited onto si111 substrate is shown in fig. The elo thin films generally contain epitaxially grown layers which are formed on a sacrificial layer disposed on or over a substrate, such as a wafer. Yablonovitch march 1990 updated may 1996 a introduction epitaxial lift off elo permits the integration of illv films and devices onto arbitrary material substrates. Laser liftoff of epitaxial thin film structures stanford university office. Electronic devices made from single crystal thin films attached to inexpensive support substrates offer. Pdf etching alas with hf for epitaxial liftoff applications.
To overcome the drawback of crack formation in the epilayer during the elo process, various patterned cu substrates were. Energy procedia 38 20 919 925 the liftoff process, which separates the epitaxial layer from the substrate, is a crucial step in the psi process. Epitaxial liftoff process for gallium arsenide substrate reuse and flexible electronics chengwei cheng, kuenting shiu, ning li, shujen han, leathen shi, devendra k. View the article pdf and any associated supplements and figures for a period of 48 hours. We reach a finesse as high as 4,100 with this configuration limited by the reflectivity of the dielectric mirrors and not by scattering at the semiconductor mirror interface, demonstrating that the epitaxial liftoff procedure is a promising procedure for cavity quantum electrodynamics in the solid state. Kilian wasmer3 1opticomp networks, attleboro, ma, 02703 usa phone. The advantage of epitaxial liftoff is that the heteroepitaxy of gaasonsi is not required. For the first time epitaxial liftoff gaas solar cells. Liftoff is applied in cases where a direct etching of structural material would have undesirable effects on the layer below. Jessica adams, microlink devices, epitaxial lift off iii. By performing the epitaxial liftoff elo process, the led device can be transferred from gaas to cu substrate. The absorber layer needs to be defectfree after the liftoff.
Embodiments of the invention generally relate to epitaxial lift off elo thin films and devices and methods used to form such films and devices. Advanced epitaxial liftoff quantum dot photovoltaic devices advanced epitaxial liftoff quantum dot photovoltaic devices 1 submitted by drupal on wed, 102320 18. Wo2009155122a3 epitaxial lift off stacks and methods. The lens serves almost all the patents and scholarly work in the world as a free, open and secure digital public good, with user privacy a paramount focus. We describe the use of the epitaxial liftoff technique to remove thin layers of inas from the gaas substrates on which they. Epitaxial liftoff of electrodeposited singlecrystal gold.
The prospects for, and benefits of fabrication processing using epitaxial liftoff elo using band gap selective photoelectrochemical pec etching techniques are also examined. Epilayers of 255 nm thickness containing quantum wells are lifted off their substrates and redeposited onto polyimide coated gaas. Tatsuro maeda1, hiroyuki ishii1, taro itatani1, tomoyuki takada2, masahiko hata2, and tetsuji yasuda 1. Researchers at the university of michigan in the usa have dramatically reduced the material and fabrication costs of gaas solar cells by using an accelerated, nondestructive epitaxial lift. Usher application of epitaxial liftoff to optoelectronic material studies. Gon membranes formed by reorganization of cylindrical pores during annealing enable the growth and transfer of gaas cells and substrate reuse. Chapter 3 hybrid integration using the epitaxial lift off. Jessica adams, microlink devices, epitaxial lift off iii v solar cell for high temperature operation alingap subcell tunnel junction ingaas subcell. Dry epitaxial lift off for high efficiency solar cells dr. The present application is a nonprovisional application claiming the benefit of u. Pdf epitaxial liftoff and its applications peter van.
Dryepitaxial liftoff for high efficiency solar cells. Liftoff is a cheap alternative to etching in a research context, which permits a slower turnaround time. Highpower vertical gan electronic devices formed by. Photoconductive switch using epitaxial liftoff low. The epitaxial liftoff process everything about solar energy. The inplane order of the spincoated materials can be seen in the scanning electron micrographs sems and optical micrographs in. These cells are separated from their gaas substrate by the epitaxial lift.