光電科技 LED: Materials and Device Aspects 授課教師 : 龔 志 榮 教授 國立中興大學物理學系 中華民國一○二年四月二十二日 1

§ 1-1 Optical Semiconductor Materials *Elemental semiconductors ： Si, Ge, （ used in photodiodes only ） *Compound semiconductors Ⅲ - Ⅴ compounds ＆ alloys Ⅳ compounds ＆ alloys Ⅰ - Ⅲ - Ⅵ 2 compounds Ⅱ - Ⅳ - Ⅴ 2 compounds Ⅳ - Ⅳ compounds For applications in light emitting devices like LEDs and LDs as well as photodiodes （ solar cells ＆ photodetectors ） 2

*Bonding and Band structure in semiconductors 3

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cross-section of diffusion fabricated LED

light emitting in the pn junction

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EQE of LEDs in the visible spectrum

LED materialSubstrateTypeWavelength(nm)ColorEfficiency InGaNSapphireD UV-RedMedium-High AlGaInPGaAsD560GreenMedium AlGaInPGaPD570GreenMedium AlGaInPGaPD590YellowHigh AlGaInPGaPD607OrangeHigh AlGaInPGaPD RedHigh AlGaAsGaAsD RedMedium Table 1: III-V semiconductor LEDs’ wavelength, Color and Efficiency

LED materialSubstrateTypeWavelength(nm)ColorEfficiency GaAsP:NGaPI589YellowLow GaAsP:NGaPI632RedLow GaAsPGaAsD649RedLow GaP I555GreenLow GaP:NGaPI565GreenLow GaP:N,NGaPI590YellowLow GaP:ZnOGaPI699RedMedium AlGaAs:SiGaAsD IRHigh GaAs:SiGaAsD IRHigh

Cross-sectional schematic of a flip chip ( 覆晶 ) GaN LED

InGaAs LED containing a photonic crystal

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光電科技 LED: Recent Advances and Applications 授課教師 : 龔 志 榮 教授 國立中興大學物理學系 中華民國一○二年五月二十日 50

Internal Quantum Efficiency Enhancement 52

Cheng-Liang Wang, Jyh-Rong Gong,* Ming-Fa Yeh, Bor-Jen Wu, Wei-Tsai Liao, Tai-Yuan Lin, and Chung-Kwei Lin 53 IEEE Photonic Technology Letters 18 (2006) 1497 * Department of Physics, National Chung Hsing University, TAIWAN, R.O.C.

GaN-based LED structures w/wo SPSLs C. L. Wang et al. IEEE Photon. Tech. Lett. 18 (2006) 1497

DCXRD and EPD of GaN-based LEDs vs. SPSL set numbers C. L. Wang et al. IEEE Photon. Tech. Lett. 18 (2006) 1497

EL and I-V characteristics C. L. Wang et al. IEEE Photon. Tech. Lett. 18 (2006) 1497

InGaN/GaN multi-quantum wells A cross-sectional TEM image mapping of the SPSL-inserted LED structure 2 sets of short period superlattices 500nm 100nm u-GaN n-GaN p-GaN n-GaN C. L. Wang et al. IEEE Photon. Tech. Lett. 18 (2006) 1497

Current-voltage charateristics C. L. Wang et al. IEEE Photon. Tech. Lett. 18 (2006) 1497

59 Cheng-Liang Wang, Ming-Chang Tsai, Jyh-Rong Gong,* Wei-Tsai Liao, Ping-Yuan Lin, Kuo- Yi Yen, Chia-Chi Chang, Hsin-Yueh Lin, and Shen-Kwang Hwang * Department of Physics, National Chung Hsing University, TAIWAN, R.O.C. Materials Science & Engineering B 138 (2007) 180

According to the standard Shockley model, the I–V relationship of a forward-biased p–n junction can be approximated by I = Is exp(q V/ηkT), where Is, q, k, η and T, respectively, are saturation current of the diode, electron charge, Boltzmann constant, and ideality factor and absolute temperature of the diode. 60

Semilogarithmic I–V plots of the forward-biased In 0.2 Ga 0.8 N/GaNMQWLEDs having (a) zero-set, (b) one-set, (c) two-set, and (d) three-set Al 0.3 Ga 0.7 N/GaN SPSL insertion. C. L. Wang et al. MSE B 138 (2007) 180

Typical optical surface morphologies of etched In 0.2 Ga 0.8 N/GaN MQW LEDs having (a) zero-, (b) one-, (c) two-, and (d) three-set Al 0.3 Ga 0.7 N/GaN SPSL insertion. C. L. Wang et al. MSE B 138 (2007) 180

Typical I–V characteristics of the reverse-biased In 0.2 Ga 0.8 N/GaNMQW LEDs (1) without SPSL insertion, (2) with one set of Al 0.3 Ga 0.7 N/GaN SPSL insertion, (3) with two sets of Al 0.3 Ga 0.7 N/GaN SPSL insertion, and (4) with three sets of Al 0.3 Ga 0.7 N/GaN SPSL insertion, respectively. The inset exhibits plots of the corresponding EL intensity vs. emissionwavelength of the two LEDs having no SPSL and two sets of SPSL operated at 20 mA.

C. L. Wang et al. MSE B 138 (2007) 180

Wei-Tsai Liao, Jyh-Rong Gong,* Cheng-Liang Wang, Wei-Lin Wang, Chih-Chang Tsuei, Cheng-Yen Lee, Keh-Chang Chen, Jeng-Rong Ho, and Ren C. Luo 65 Electrochemical and Solid-State Letters, 10 1 H5-H7 (2007) * Department of Physics, National Chung Hsing University, TAIWAN, R.O.C.

Typical 0002 DCXRD curves of the In 0.1 Ga 0.9 N/Al 0.03 Ga 0.97 N MQW LED structures grown on c- and a-plane sapphire substrates. Insets: the corresponding XTEM micrographs of the LEDs near MQW area, respectively W. T. Liao et al. Electrochem. Solid-State Lett. 10 (2007) H5

Characteristics of the In 0.1 Ga 0.9 N/Al 0.03 Ga 0.97 N MQW LEDs grown on c- and a-plane sapphire substrates W. T. Liao et al. Electrochem. Solid-State Lett. 10 (2007) H5

Plots of EL intensity vs forward current of the In0.1Ga0.9N/Al0.03Ga0.97N MQW LEDs grown on c- and a-plane sapphire substrates. Inset: a typical room-temperature EL spectra measured at 20 mA for the In0.1Ga0.9N/Al0.03Ga0.97N MQW LEDs grown on c- and a-plane sapphire substrates. W. T. Liao et al. Electrochem. Solid-State Lett. 10 (2007) H5

Typical FESEM surface morphologies of the etched In 0.1 Ga 0.9 N/Al 0.03 Ga 0.97 N MQW LEDs grown on a c- and b a-plane sapphire substrates W. T. Liao et al. Electrochem. Solid-State Lett. 10 (2007) H5

External Quantum Efficiency Enhancement 70

Kuo-Yi Yen, Chien-Hua Chiu, Chun-Wei Li, Chien-Hua Chou, Pei-Shin Lin, Tzu-Pei Chen,Tai-Yuan Lin, and Jyh-Rong Gong* 71 * Department of Physics, National Chung Hsing University, TAIWAN, R.O.C. IEEE PhotonicTechnologyLett.ers 24 (2012) 2105

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Typical I-V curves of (a) N 2 -annealed n + -GZO contacts along with an ITO contact on p-GaN/sapphire templates and (b) forward-biased InGaN/GaN MQW LEDs with an as-deposited n + -GZO TCL, an ITO TCL and n + -GZO TCLs being N 2 -annealed at 400 °C, 500 °C, 600 °C, 700 °C, and 800 °C. K. Y. Yen et al. IEEE Photon.Tech.Lett. 24 (2012) 2105

Schematic showing electron tunneling in a reverse-biased n + GZO/p-GaN hetero-junction K. Y. Yen et al. IEEE Photon. Tech. Lett. 24 (2012) 2105

K. Y. Yen et al. IEEE Photon.Tech.Lett. 24 (2012) 2105 (a)–(f) θ-2θ XRD plots of as- deposited n + -GZO TCL and n + -GZO TCLs on GaN/c-sapphire substrates being annealed at 400 °C, 500 °C, 600 °C, 700 °C, and 800 °C for 5 min in N 2 ambient.

Light output powers of InGaN/GaN MQW LEDs with as-deposited n + -GZO, 400 °C N 2 -annealed n + -GZO and commercial ITO TCLs K. Y. Yen et al. IEEE Photon. Tech. Lett. 24 (2012) 2105

Optical transmittances of as-deposited n + -GZO, 400 °C N 2 -annealed n + -GZO and ITO films deposited on c-sapphire substrates K. Y. Yen et al. IEEE Photon. Tech. Lett. 24 (2012) 2105

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