Nonalloyed Ohmic Contacts for HEMTs Using n⁺-lnGaAs Layers Grown by MOVPE

Mizuhisa NIHEI, Naoki HARA, Haruyoshi SUEHIRO, Shigeru KURODA

Summary :

We fabricated and investigated HEMTs with nonalloyed ohmic contacts using highly conductive n⁺-ln_0.5Ga_0.5 As contact layers. We optimized the growth condition of n⁺-In_0.5 Ga_0.5As contact layers by MOVPE. Using WSi/W nonalloyed ohmic electrodes, we fabricated InGaP/InGaAs/GaAs pseudomorphic HEMTs with thermal stability of 500 for 30 minutes. In order to examine the scalability of HEMT devices, we tried to reduce the total size of HEMT devices to 3.2 µm using nonalloyed ohmic electrodes, which is the smallest value as far as we know. We could reduce the nonalloyed ohmic contact length L_oh to 0.4 µm without degrading the device characteristics. Reducing the n⁺-In_0.5Ga_0.5As contact length L_IGA to l µm however, decreased the transconductance g_m by about 20%. We found that the scaling of the conventional nonalloyed HEMT structure is limited by L_IGA.

• Publication: IEICE TRANSACTIONS on Electronics Vol.E77-C No.9 pp.1431-1436
• Publication Date: 1994/09/25
• Type of Manuscript: Special Section PAPER (Special Issue on Heterostructure Devices and Epitaxial Growth Techniques)

Authors

Mizuhisa NIHEI
Naoki HARA
Haruyoshi SUEHIRO
Shigeru KURODA

Keyword

nonalloyed ohmic contact,  n⁺-InGaAs,  MOVPE,  HEMT