InGaN/GaN multiple-quantum-well light-emitting diode (LED) structures inclu
ding a Si-doped In0.23Ga0.77N/GaN short-period superlattice (SPS) tunneling
contact layer were grown by metalorganic vapor phase epitaxy. The In0.23Ga
0.77N/GaN(n(+))-GaN(p) tunneling junction, which the low-resistivity n(+)-I
n0.3Ga0.7N/GaN SPS instead of high-resistivity p-type GaN as a top contact
layer, allows the reverse-biased tunnel junction to form a "ohmic" contact.
In this structure, the sheet electron concentration of Si-doped In0.23Ga0.
77N/GaN SPS is around I x 10(14)/cm(2), leading to an averaged electron con
centration of around 1 x 10(20)/cm(3). This high-conductivity SPS would lea
d to a low-resistivity ohmic contact (Au/Ni/SPS) of LED. Experimental resul
ts indicate that the LEDs can achieve a lower operation voltage of around 2
.95 V, i.e., smaller than conventional devices which have an operation volt
age of about 3.8 V.