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- Bengtsson, Stefan, 1961, et al.
(författare)
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Integration of silicon and diamond, aluminum nitride or aluminum oxide for electronic materials
- 1999
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Ingår i: conference proceedings:III-V and IV-IV Materials and Processing Challenges for Highly Integrated Microelectronics and Optoelectronics. Symposium.. ; , s. 133-
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Konferensbidrag (refereegranskat)abstract
- Material integration for the formation of advanced silicon-on-insulator materials by wafer bonding and etch-back is discussed. Wafer bonding allows the combining of materials that it is not possible to grow on top of each other by any other technique. In our experiments, polycrystalline diamond, aluminum nitride or aluminum oxide films with thickness of 0.1-5 μm were deposited on silicon wafers. Bonding experiments were made with these films to bare silicon wafers with the goal of forming silicon-on-insulator structures with buried films of polycrystalline diamond, aluminum nitride or aluminum oxide. These silicon-on-insulator structures are intended to address self-heating effects in conventional silicon-on-insulator materials with buried layers of silicon dioxide. The surfaces of the deposited diamond films were, by order of magnitude, too rough to allow direct bonding to a silicon wafer. In contrast the deposited aluminum nitride and aluminum oxide films did allow direct bonding to silicon. Bonding of the diamond surface to silicon was instead made through a deposited and polished layer of polycrystalline silicon on top of the diamond. In the case of the aluminum nitride electrostatic bonding was also demonstrated. Further, the compatibility of these insulators to silicon process technology was investigated
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| 2. |
- Bergmann, Michael Alexander, 1989, et al.
(författare)
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Towards ultraviolet and blue microcavity lasers
- 2018
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Ingår i: Northen Optics and Photonics conference. - 9789163964886 ; 2018
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Konferensbidrag (refereegranskat)abstract
- The development of III-nitride-based (Al,Ga,In(N)) microcavity lasers is a challenging task. Significant progress in recent years has resulted in realizations of electrically pumped devices with optical output power in the mW-range and with threshold current densities below 20 kA/cm2. However, to become practical, the lifetime and power conversion efficiency of these devices must be improved. Among the challenges are achieving transverse optical mode confinement, highreflectivity mirrors and control over the resonator length. We will highlight our theoretical work on transverse optical mode confinement, emphasising the overwhelming risk of ending up with an optically anti-guided cavity, and its consequences such as very high optical losses that easily could double the threshold gain for lasing. We will show some anti-guided cavities with reasonable threshold gain and built-in modal discrimination. However, all anti-guided cavities are very sensitive to temperature effects and small structural changes in the cavity caused by fabrication imperfections. We have explored electrically conductive distributed Bragg reflectors (DBRs) in both AlN/GaN and ZnO/GaN. The AlN/GaN DBRs were grown with different strain-compensating interlayers, and the DBR without interlayers had the lowest vertical resistivity with a specific series resistance of 0.044 cmfor eight DBRpairs. In the ZnO/GaN DBR, the measured resistance was dominated by lateral and contact contributions, setting a lower measurable limit of ~10 for three DBR-pairs. Numerical simulations show the importance of having in-plane strained layers in the ZnO/GaN DBR, since that leads to cancellation of the spontaneous and piezoelectric polarization. This results in a dramatically reduced vertical resistance, potentially three orders of magnitude lower than what could be measured. cm An alternative to an epitaxially grown DBR is a dielectric DBR, which offers high reflectivity over a broader wavelength range, relaxing the requirements on resonator length control. To deposit a dielectric DBR on the bottom side of the cavity, the sample must first be bonded to a carrier wafer before the substrate can be removed. We used thermocompression gold-gold bonding to successfully bond the laser structure to a Si carrier wafer. The subsequent substrate removal is a challenging process due to the chemical inertness of the III-nitride-based materials. A doping-dependent electrochemical etch technique was used, which allows for the selective removal of a sacrificial (n-doped) layer between the cavity and the substrate. This resulted in nm-precise cavity lift-off with a low root-mean-square surface roughness down to 0.3 nm. Thus, the process is suitable for the fabrication of high-quality optical devices such as microcavity lasers. In addition, the technique offers a new alternative to create III-nitridebased optical resonators, mechanical resonators, thin film LEDs and transistors.
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| 7. |
- Hedsten, Karin, 1964, et al.
(författare)
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Downscaling Optical Biosensing System
- 2008
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Ingår i: Proceedings of Micro System Workshop 2008 (MSW08) 6-7 Maj, Göteborg, Sweden. ; MSW08, s. S2-6, s. 205-
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Konferensbidrag (refereegranskat)
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| 10. |
- Borgentun, Carl, 1979, et al.
(författare)
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Full characterization of a semiconductor laser beam by simultaneous capture of the near- and far-field
- 2010
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Ingår i: Conference Digest - IEEE International Semiconductor Laser Conference. - 0899-9406. - 9781424456833 ; , s. 127-128
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- We present a new measurement technique for fully characterizing a semiconductor laser beam. The reflections from both surfaces of a planoconvex lens are used to simultaneously capture the near- and far-field. The optical phase is then retrieved using the Gerchberg-Saxton algorithm with improved numerical operations.
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