Epitaxial Bi∕GaAs diodes via electrodeposition

Abstract

Epitaxial Bi/ GaAs diodes have been formed by electrodeposition from bismuth nitrate and ammonium sulfate ͑͑NH 4 ͒ 2 SO 4 ͒ aqueous solutions. Bi grows ͑0001͒ oriented on both GaAs ͑111͒B and ͑001͒ substrates while it tilts 16°to a ͑011 គ 8͒ surface orientation for ͑011͒ GaAs. The metal orients in all cases with its ͕112 គ 0͖ planes parallel the GaAs ͕110͖ planes. Diodes prepared on ͑001͒, ͑111͒B, and ͑011͒ wafers have current-voltage barrier heights ⌽ B IV that vary from 0.74, to 0.76, to 0.83 eV ͑n = 1.01-1.11͒, respectively. These barrier heights straggle values from earlier reports for polycrystalline Bi deposited by ultrahigh vacuum techniques or electrodeposition. Barrier heights measured from high frequency, capacitance-voltage characteristics are higher than the ⌽ B IV results, 0.06-1.5 eV, as a function of the GaAs orientation, increasing in value in order of ͑011͒, ͑001͒, to ͑111͒B. This is explained by a combination of image force lowering and field emission corrections, and interface state/dipoles that are likely dependent on the GaAs orientation and on the degree of ͑0001͒ Bi alignment. These results are supported by cross-sectional transmission electron microscopy investigations indicating abrupt Bi/ GaAs interfaces without evidence of a significant interfacial oxide or reacted layer.

Electrodeposition of Bi Thin Films on n-GaAs(111)B. II. Correlation between the Nucleation Process and the Structural and Electrical Properties

“…The values obtained for  B are in agreement with those found in the literature for other n-GaAs Schottky barriers obtained by electrodeposition [17][18][19][20] . The dependence of  B with  SEI is complex ( Figure 5.b).…”

The analysis of lateral distribution of barrier height in identically prepared Co/n-Si Schottky diodes

“…Moreover, electrodeposition method provides the possibility of depositing film structures different from those being produced from the vapour phase. For example, the electrodeposition method does not require a pretreatment to activate the surface [22][23][24][25]. The electrodeposition is an advantageous alternative to the common expensive physical technologies for the metallization of semiconductors and it is useful to avoid passivation processes occurring during the deposition process [22][23][24][25].…”

Mixed Effects of the Atomic Arrangement and Surface Chemistry on the Electrodeposition of Bi Thin Films on n-GaAs Substrates

“…Therefore, the surface orientation strongly affects the electrochemical properties of the substrate surface and the electrical properties of the metal-semiconductor interface 24,[26][27][28] . Although other authors have studied the electrodeposition of Bi on GaAs substrates with different surface orientations 19,[29][30][31] , the discrimination between the effect of surface atomic arrangement and surface chemistry has not been done yet.…”

“…For these purposes, electrodeposition has proved to be a suitable technique since high-quality Bi thin films, and other metallic layers, can be grown onto semiconducting substrates. In fact, high-quality Bi films have been electrodeposited on n-GaAs single-crystal substrates, leading to Bi/GaAs Schottky diodes [19][20][21][22] . The use of single-crystal semiconductors as substrates makes necessary the knowledge of its crystal structure and chemical composition because both of them lead to the specific energy band structure and, therefore, the specific electronic properties of the semiconductor.…”