Structural and optical quality of GaN/metal/Si heterostructures fabricated by excimer laser lift-off

Wong, William S.; Cho, Y.; Weber, E. R.; Sands, T.; Yu, K. M.; Krüger, Joachim; Wengrow, A. B.; Cheung, N.W.

doi:10.1063/1.124861

Cited by 58 publications

(32 citation statements)

References 17 publications

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“…As to GaN film, the PL peak shows a red shift compared with that of the as-grown samples due to the smaller compressive stress existing in the transferred film [11] . While EL peak of the GaN MQW LEDs films show blue-shift [12] , red-shift [12] and no shift [13] , the uncertain shift may be attributed to the precision processing parameters of laser lift-off which is very difficult to control.…”

Section: Resultsmentioning

confidence: 98%

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Different properties of GaN-based LED grown on Si(111) and transferred onto new substrate

et al. 2006

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InGaN MQW LEDs, grown by metal-organic chemical vapor deposition (MOCVD) on Si(111) substrates, were successfully bonded and transferred onto new Si substrate. After chemical etching Si(111) substrate and inductively coupled plasma (ICP)etching the transferred LED film to Si-doped layer, a vertical structure GaN blue LEDs were then fabricated. The characteristics of the lateral structure LED (grown on Si) and the vertical structure LED (bonded on Si) were investigated. It shows the performance of vertical structure LEDs had obviously been improved compared to the lateral structure LEDs and the tensile stress in GaN layer of vertical structure LEDs is smaller than that in lateral structure LEDs.

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Section: Resultsmentioning

confidence: 98%

“…Transferring GaN-based film to new substrate by wafer bonding and laser lift-off technique has been demonstrated by several groups [11][12][13] . As to GaN film, the PL peak shows a red shift compared with that of the as-grown samples due to the smaller compressive stress existing in the transferred film [11] .…”

Section: Resultsmentioning

confidence: 99%

Different properties of GaN-based LED grown on Si(111) and transferred onto new substrate

et al. 2006

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“…The detailed physical properties of the HEMTs were previously published [5]. The HEMTs were separated from the sapphire substrates using a Lambda Physik excimer laser operating at wavelength l ¼ 248 nm with a laser fluence of 400 mJ cm À2 [6]. A typical debonded device is shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

High-resolution X-ray diffraction study of laser lift-off AlGaN/GaN HEMTs grown by MOCVD method

Leung

Chan

Fong

et al. 2007

Journal of Crystal Growth

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“…The laser light is irradiated from the back surface of the sapphire substrate, and will be absorbed by the interface of GaN and sapphire, yielding metallic Ga and gas N 2 .Then the GaN and the sapphire will be separated [4][5][6][7][8] .…”

mentioning

confidence: 99%

Laser lift-off technique and the re-utilization of GaN-based LED films grown on sapphire substrate

Huang

Zheng

Liu

2008

Optoelectron. Lett.

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A thin GaN LED film, grown on 2-inch-diameter sapphire substrates, is separated by laser lift-off. Atom force microscopy (AFM) and the double-crystal X-ray diffraction (XRD) have been employed to characterize the performance of GaN before and after the lift-off process. It is demonstrated that the separation and transfer processes do not alter the crystal quality of the GaN films obviously. InGaN/ GaN multi-quantum-wells (MQW's) structure is grown on the separated sapphire substrate later and is compared with that grown on the conventional substrate under the same condition by using PL and XRD spectrum.GaN-based electronic and optoelectronic devices are used widely [1] . However, it is difficult to get the large-size single GaN crystal, and GaN films are usually grown on dissimilar substrates such as sapphire. Sapphire as the most commonly used substrate still imposes constrains on the GaN film quality due to the mismatch of lattice and the thermal-expansion coefficient between the sapphire and GaN [2] . The sapphire substrate also inhibits the performance of LEDs, LDs and transistor devices due to its poor thermal and electrical conductivity.The poor thermal conductivity of sapphire prevents efficient dissipation of heat generated by GaN-based high-current devices, and consequently inhibits the performance of the devices. In addition, for devices processed on sapphire substrates, all contacts must be made from the topside, which will result in a spreading-resistance penalty and will increase operating voltages [3] . To solve these problems, GaN epilayers can be transferred to another substrate with good thermal conductivity, such as Si or metallic materials, by using wafer bonding and laser lift-off (LLO) techniques.The lift-off process (LLO) is performed using an ultraviolet (UV) laser. The laser light is irradiated from the back surface of the sapphire substrate, and will be absorbed by the interface of GaN and sapphire, yielding metallic Ga and gas N 2 .Then the GaN and the sapphire will be separated [4][5][6][7][8] .The steps of grinding and polishing process must be taken on the rear surface of the sapphire wafer after the electrode preparation in commercial LEDs. However, due to the high rigidity and fragility of sapphire with a hardness level of 9 in the classical Mohs hardness scale, the mechanical process of sapphire substrate is hard, which increases the difficulty of the mechanical process and the re-utilization of sapphire. In fact, the above problems can be solved and the sapphire substrates will be re-utilizated by LLO technique to transfer the GaN film from the Si substrates. In this paper, GaN LED films, grown on 2-inch-diameter sapphire substrates, are bonded and separated by LLO. Then a InGaN/ GaN multiquantum-wells (MQW's) structure is grown on the separated sapphire substrate again and is compared with that grown on the conventional substrate under the same condition.The InGaN/GaN multiple-quantum-wells (MQW's) LED structures used in this paper are grown on (0001)-oriented sapphire substrates...

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Structural and optical quality of GaN/metal/Si heterostructures fabricated by excimer laser lift-off

Cited by 58 publications

References 17 publications

Different properties of GaN-based LED grown on Si(111) and transferred onto new substrate

Different properties of GaN-based LED grown on Si(111) and transferred onto new substrate

High-resolution X-ray diffraction study of laser lift-off AlGaN/GaN HEMTs grown by MOCVD method

Laser lift-off technique and the re-utilization of GaN-based LED films grown on sapphire substrate

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