Limits...
Enhanced performance of photonic crystal GaN light-emitting diodes with graphene transparent electrodes.

Ge HL, Xu C, Xu K, Xun M, Wang J, Liu J - Nanoscale Res Lett (2015)

Bottom Line: Specially, we found that the part of the graphene suspending over the air hole of the PC structure was of much higher conductivity, which reduced the average sheet resistance of the graphene transparent conducting electrode and improved the current spreading of the PC LED.Therefore, the work voltage of the DGTE-PC LED was obviously decreased, and the output power was greatly enhanced.The results show that the etching of PC structure results in the degradation of the current spreading and that the graphene transparent conducting electrode can offer an uniform current spreading in the DGTE-PC LED. 85.60.Jb; 68.65.Pq; 42.70.Qs.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing, 100124 People's Republic of China.

ABSTRACT

Unlabelled: The two-dimensional (2D) triangle lattice air hole photonic crystal (PC) GaN-based light-emitting diodes (LED) with double-layer graphene transparent electrodes (DGTE) have been produced. The current spreading effect of the double-layer graphene (GR) on the surface of the PC structure of the LED has been researched. Specially, we found that the part of the graphene suspending over the air hole of the PC structure was of much higher conductivity, which reduced the average sheet resistance of the graphene transparent conducting electrode and improved the current spreading of the PC LED. Therefore, the work voltage of the DGTE-PC LED was obviously decreased, and the output power was greatly enhanced. The COMSOL software was used to simulate the current density distribution of the samples. The results show that the etching of PC structure results in the degradation of the current spreading and that the graphene transparent conducting electrode can offer an uniform current spreading in the DGTE-PC LED.

Pacs: 85.60.Jb; 68.65.Pq; 42.70.Qs.

No MeSH data available.


The I to V characteristics of the LEDs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4385276&req=5

Fig6: The I to V characteristics of the LEDs.

Mentions: Figure 6 shows the current–voltage (I to V) characteristics of the five LED samples at an input current of 20 mA. The forward voltage of the A2#, A0#, B2#, B1#, and B0# samples is 3.3, 4.3, 3.4, 4, and 4.9 V, respectively. The work voltage of the A2# is 1 V lower than that of A0#, while the work voltage of the B2# sample is 1.5 V lower than that of B0#. This indicates that the double-layer graphene can greatly reduce the series resistance of LED, especially for PC LED due to improving the current spreading. The work voltage of the B2# sample is 0.6 V lower than that of B1#, showing the better effect of double-layer graphene. The work voltage of the B0# sample is 0.6 V higher than that of A0#, indicating the degraded current spreading in the PC LED because of a surface defect induced by ICP etching [15,27,28]. A parameter K is introduced to represent the overall degradation level of the forward I to V characteristics of the PC LED, compared with the conventional LED. K = △V/Vconventional, where the △V represents the work voltage difference between the PC LED and conventional LED and the Vconventional stands for the work voltage of the conventional LED at I = 20 mA, respectively. The smaller the K is, the weaker the degradation of the forward I to V characteristics of the PC LED is. According to Figure 6, for B2# and A2# samples, K = 0.1/3.3 = 0.03. Kim Dong Ho and Kim Tae Sun observed the degradation of the forward I to V characteristic of PC LED due to etching PC structure, and they used some other transparent electrodes (ITO et al.) to improve the current spreading of the PC LEDs [5,11]. However, K = 0.12 and K = 0.15 can be obtained from their results, which is much higher than that of our results. Therefore, the advantage of the double-layer graphene electrode for the PC LED is obvious.Figure 6


Enhanced performance of photonic crystal GaN light-emitting diodes with graphene transparent electrodes.

Ge HL, Xu C, Xu K, Xun M, Wang J, Liu J - Nanoscale Res Lett (2015)

The I to V characteristics of the LEDs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4385276&req=5

Fig6: The I to V characteristics of the LEDs.
Mentions: Figure 6 shows the current–voltage (I to V) characteristics of the five LED samples at an input current of 20 mA. The forward voltage of the A2#, A0#, B2#, B1#, and B0# samples is 3.3, 4.3, 3.4, 4, and 4.9 V, respectively. The work voltage of the A2# is 1 V lower than that of A0#, while the work voltage of the B2# sample is 1.5 V lower than that of B0#. This indicates that the double-layer graphene can greatly reduce the series resistance of LED, especially for PC LED due to improving the current spreading. The work voltage of the B2# sample is 0.6 V lower than that of B1#, showing the better effect of double-layer graphene. The work voltage of the B0# sample is 0.6 V higher than that of A0#, indicating the degraded current spreading in the PC LED because of a surface defect induced by ICP etching [15,27,28]. A parameter K is introduced to represent the overall degradation level of the forward I to V characteristics of the PC LED, compared with the conventional LED. K = △V/Vconventional, where the △V represents the work voltage difference between the PC LED and conventional LED and the Vconventional stands for the work voltage of the conventional LED at I = 20 mA, respectively. The smaller the K is, the weaker the degradation of the forward I to V characteristics of the PC LED is. According to Figure 6, for B2# and A2# samples, K = 0.1/3.3 = 0.03. Kim Dong Ho and Kim Tae Sun observed the degradation of the forward I to V characteristic of PC LED due to etching PC structure, and they used some other transparent electrodes (ITO et al.) to improve the current spreading of the PC LEDs [5,11]. However, K = 0.12 and K = 0.15 can be obtained from their results, which is much higher than that of our results. Therefore, the advantage of the double-layer graphene electrode for the PC LED is obvious.Figure 6

Bottom Line: Specially, we found that the part of the graphene suspending over the air hole of the PC structure was of much higher conductivity, which reduced the average sheet resistance of the graphene transparent conducting electrode and improved the current spreading of the PC LED.Therefore, the work voltage of the DGTE-PC LED was obviously decreased, and the output power was greatly enhanced.The results show that the etching of PC structure results in the degradation of the current spreading and that the graphene transparent conducting electrode can offer an uniform current spreading in the DGTE-PC LED. 85.60.Jb; 68.65.Pq; 42.70.Qs.

View Article: PubMed Central - PubMed

Affiliation: The Key Laboratory of Optoelectronics Technology, Ministry of Education, Beijing University of Technology, Beijing, 100124 People's Republic of China.

ABSTRACT

Unlabelled: The two-dimensional (2D) triangle lattice air hole photonic crystal (PC) GaN-based light-emitting diodes (LED) with double-layer graphene transparent electrodes (DGTE) have been produced. The current spreading effect of the double-layer graphene (GR) on the surface of the PC structure of the LED has been researched. Specially, we found that the part of the graphene suspending over the air hole of the PC structure was of much higher conductivity, which reduced the average sheet resistance of the graphene transparent conducting electrode and improved the current spreading of the PC LED. Therefore, the work voltage of the DGTE-PC LED was obviously decreased, and the output power was greatly enhanced. The COMSOL software was used to simulate the current density distribution of the samples. The results show that the etching of PC structure results in the degradation of the current spreading and that the graphene transparent conducting electrode can offer an uniform current spreading in the DGTE-PC LED.

Pacs: 85.60.Jb; 68.65.Pq; 42.70.Qs.

No MeSH data available.