An Al x In1−x As/GaAs heterojunction ultra-thin film solar cell with 20% efficiency

Experimental study of GaN based blue light emitting diodes with a thin AlInN layer in front of the electron blocking layer

“…However, the reduction of emission efficiency at high injection current density, which is often called efficiency droop, seriously restricts the InGaN/GaN based LEDs application in the realization of high-power, high-brightness illumination [2] . Various models for the efficiency droop have been proposed, including the ones with Auger recombination [3,4] , polarization-assisted electron leakage [5,6] , lack of hole injection [7,8] , defects [9] and junction heating [10] . Among these factors, electron leakage out of the active region as well as inefficient hole injection has been identified as the major reasons for efficiency droop [11] .…”

Effects of Mg-doping concentration on the characteristics of InGaN based solar cells

“…However, when the Mg-doping concentration is over 1×10 18 cm -3 , the crystal quality degrades, which results in the reduction of the external quantum efficiency (EQE), short circuit current density and open circuit voltage. As a result, the sample with a slight Mg-doping concentration of 5×10 17 cm -3 exhibits the highest conversion efficiency.Nowadays, InGaN ternary alloys have drawn great attention in the field of optoelectronics due to their unique physical characteristics, including excellent radiation resistance, good thermal conductivity, large absorption coefficients (~10 5 cm -1 ) [1] and wide band gap (varying from 0.64 eV to 3.4 eV) covering most of the solar spectrum [2][3][4][5][6][7] , which makes them suitable for producing solar cells.Until now, there are several difficulties in the fabrication of InGaN based solar cells with high efficiency. Firstly, the hole mobility in the InGaN material is about 10 cm 2 /(V·s), but the electron mobility in the InGaN material is about 100 cm 2 /(V·s), so there is relatively large lack of holes in InGaN based optoelectronic devices.…”

“…Unfortunately, the fabrication of solar cells with large In proportion remains a challenge, because of the large lattice mismatch between indium nitride and gallium nitride. When the layer thickness and/or In proportion of InGaN alloys increase, In clusters in InGaN films easily lead to phase separation, which results in the lower open circuit voltages (V oc ) compared with theoretical values, the low fill factors (FFs) and degradation of the short-circuit current density (J sc ) [6][7][8][9][10] .To partially overcome the In incorporation limitation in thick layers, many researchers have adopted multiple quantum wells (MQWs) or superlattice absorbing layers [11][12][13] . InGaN based MQW optical devices can not only obtain higher crystal quality of InGaN absorption layers embedded between GaN barriers, but also optimize V oc and J sc independently by adjusting parameters of quantum barrier and well materials [14] .…”

“…Nowadays, InGaN ternary alloys have drawn great attention in the field of optoelectronics due to their unique physical characteristics, including excellent radiation resistance, good thermal conductivity, large absorption coefficients (~10 5 cm -1 ) [1] and wide band gap (varying from 0.64 eV to 3.4 eV) covering most of the solar spectrum [2][3][4][5][6][7] , which makes them suitable for producing solar cells.…”

“…Unfortunately, the fabrication of solar cells with large In proportion remains a challenge, because of the large lattice mismatch between indium nitride and gallium nitride. When the layer thickness and/or In proportion of InGaN alloys increase, In clusters in InGaN films easily lead to phase separation, which results in the lower open circuit voltages (V oc ) compared with theoretical values, the low fill factors (FFs) and degradation of the short-circuit current density (J sc ) [6][7][8][9][10] .…”