Low Resistance Non-Alloy Ohmic Contact to p-Type GaN Using Mg-Doped InGaN Contact Layer

We investigated non-alloy Ohmic contact to p-type GaN using Mg-doped InGaN contact layer. The thickness and In mole fraction of the p-type InGaN were varied from 2 to 15 nm and from 0.14 to 0.23, respectively. Strained InGaN contact layers are effective in reducing the contact resistance. The lowest specific contact resistance of 1.1 x 10 -6 Ω cm 2 was obtained using a contact layer of 2 nm thick strained In 0.19 Ga 0.81 N. The mechanism for the lower contact resistance is ascribed to enhanced tunneling transport due to the large polarization-induced band bending at the surface as well as the high hole concentration in p-type InGaN.

[1]  Umesh K. Mishra,et al.  ENHANCED MG DOPING EFFICIENCY IN AL0.2GA0.8N/GAN SUPERLATTICES , 1999 .

[2]  K. Kumakura,et al.  High hole concentrations in Mg-doped InGaN grown by MOVPE , 2000 .

[3]  Seong Jun Park,et al.  Formation of low resistance Pt ohmic contacts to p-type GaN using two-step surface treatment , 1999 .

[4]  L. J. Chen,et al.  Low-resistance ohmic contacts to p-type GaN achieved by the oxidation of Ni/Au films , 1999 .

[5]  K. Kumakura,et al.  Activation Energy and Electrical Activity of Mg in Mg-Doped InxGa1-xN (x<0.2) , 2000 .

[6]  K. Kumakura,et al.  Efficient Hole Generation above 1019 cm-3 in Mg-Doped InGaN/GaN Superlattices at Room Temperature , 2000 .

[7]  Seong Jun Park,et al.  Metallization scheme for highly low-resistance, transparent, and thermally stable Ohmic contacts to p-GaN , 2000 .

[8]  K. Kumakura,et al.  Reduced damage of electron cyclotron resonance etching by In doping into p-GaN , 2000 .

[9]  High Room-Temperature Hole Concentrations above 10 19 cm −3 in Mg-Doped InGaN/GaN Superlattices , 2000 .

[10]  Masa-aki Suzuki,et al.  Low-resistance Ta/Ti ohmic contacts for p-type GaN , 1998 .

[11]  Michael S. Shur,et al.  Elastic strain relaxation and piezoeffect in GaN-AlN, GaN-AlGaN and GaN-InGaN superlattices , 1997 .

[12]  W. Lanford,et al.  Low resistance Ti'Pt'Au ohmic contacts to p-type GaN , 2000 .

[13]  Increased Electrical Activity of Mg-Acceptors in AlxGa1-xN/GaN Superlattices , 1999 .

[14]  Y. Li,et al.  Low-resistance ohmic contacts to p-type GaN , 2000 .

[15]  Taeil Kim,et al.  Low resistance Pd/Au ohmic contacts to p-type GaN using surface treatment , 1998 .

[16]  I. Adesida,et al.  Ti/Pt/Au ohmic contacts on p-type GaN/Al/sub x/Ga/sub 1-x/N superlattices , 2000 .